fix modules_install via NFS

Rafael reported:

I get the following error from 'make modules_install' on my test boxes:

  HOSTCC  firmware/ihex2fw
/home/rafael/src/linux-2.6/firmware/ihex2fw.c:268: fatal error: opening dependency file firmware/.ihex2fw.d: Read-only file system
compilation terminated.
make[3]: *** [firmware/ihex2fw] Error 1
make[2]: *** [_modinst_post] Error 2
make[1]: *** [sub-make] Error 2
make: *** [all] Error 2

where the configuration is that the kernel is compiled on a build box
with 'make O=<destdir> -j5' and then <destdir> is mounted over NFS read-only by
each test box (full path to this directory is the same on the build box and on
the test boxes).  Then, I cd into <destdir>, run 'make modules_install' and get
the error above.

The issue turns out to be that we when we install firmware pick
up the list of firmware blobs from firmware/Makefile.
And this triggers the Makefile rules to update ihex2fw.

There were two solutions for this issue:
1) Move the list of firmware blobs to a separate file
2) Avoid ihex2fw rebuild by moving it to scripts

As I seriously beleive that the list of firmware blobs should be
done in a fundamental different way solution 2) was selected.
Reported-and-tested-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: David Woodhouse <dwmw2@infradead.org>

firmware/.gitignore

@@ -3,4 +3,3 @@
 *.bin
 *.csp
 *.dsp
-ihex2fw

firmware/Makefile

@@ -99,10 +99,10 @@ quiet_cmd_ihex  = IHEX    $@
       cmd_ihex  = $(OBJCOPY) -Iihex -Obinary $< $@
 
 quiet_cmd_ihex2fw  = IHEX2FW $@
-      cmd_ihex2fw  = $(objtree)/$(obj)/ihex2fw $< $@
+      cmd_ihex2fw  = $(objtree)/scripts/ihex2fw $< $@
 
 quiet_cmd_h16tofw  = H16TOFW $@
-      cmd_h16tofw  = $(objtree)/$(obj)/ihex2fw -w $< $@
+      cmd_h16tofw  = $(objtree)/scripts/ihex2fw -w $< $@
 
 quiet_cmd_fwbin = MK_FW   $@
       cmd_fwbin = FWNAME="$(patsubst firmware/%.gen.S,%,$@)";		     \
@@ -165,11 +165,11 @@ $(obj)/%: $(obj)/%.ihex | $(objtree)/$(obj)/$$(dir %)
 # is actually meaningful, because the firmware has to be loaded in a certain
 # order rather than as a single binary blob. Thus, we convert them into our
 # more compact binary representation of ihex records (<linux/ihex.h>)
-$(obj)/%.fw: $(obj)/%.HEX $(obj)/ihex2fw | $(objtree)/$(obj)/$$(dir %)
+$(obj)/%.fw: $(obj)/%.HEX  | $(objtree)/$(obj)/$$(dir %)
 	$(call cmd,ihex2fw)
 
 # .H16 is our own modified form of Intel HEX, with 16-bit length for records.
-$(obj)/%.fw: $(obj)/%.H16 $(obj)/ihex2fw | $(objtree)/$(obj)/$$(dir %)
+$(obj)/%.fw: $(obj)/%.H16 | $(objtree)/$(obj)/$$(dir %)
 	$(call cmd,h16tofw)
 
 $(firmware-dirs):
@@ -186,5 +186,3 @@ targets := $(fw-shipped-) $(patsubst $(obj)/%,%, \
 # Without this, built-in.o won't be created when it's empty, and the
 # final vmlinux link will fail.
 obj-n := dummy
-
-hostprogs-y := ihex2fw

scripts/.gitignore

 #
 # Generated files
 #
+ihex2fw
 conmakehash
 kallsyms
 pnmtologo

scripts/Makefile

@@ -2,11 +2,12 @@
 # scripts contains sources for various helper programs used throughout
 # the kernel for the build process.
 # ---------------------------------------------------------------------------
+# ihex2fw:       Parser/loader for IHEX formatted data
 # kallsyms:      Find all symbols in vmlinux
 # pnmttologo:    Convert pnm files to logo files
-# conmakehash:   Create chartable
 # conmakehash:	 Create arrays for initializing the kernel console tables
 
+hostprogs-y                      := ihex2fw
 hostprogs-$(CONFIG_KALLSYMS)     += kallsyms
 hostprogs-$(CONFIG_LOGO)         += pnmtologo
 hostprogs-$(CONFIG_VT)           += conmakehash