[POWERPC] Remove generated files on make clean

dtbImage.* and several zImage. targets get created but never cleaned up.

Also, moved zImage to the clean-files line associated with all other image
results (was previously duplicated).
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/boot/Makefile

@@ -99,7 +99,7 @@ $(obj)/zImage.lds $(obj)/zImage.coff.lds $(obj)/zImage.ps3.lds: $(obj)/%: $(srct
 	@cp $< $@
 
 clean-files := $(zlib) $(zlibheader) $(zliblinuxheader) \
-		empty.c zImage zImage.coff.lds zImage.ps3.lds zImage.lds
+		empty.c zImage.coff.lds zImage.ps3.lds zImage.lds
 
 quiet_cmd_bootcc = BOOTCC  $@
       cmd_bootcc = $(CROSS32CC) -Wp,-MD,$(depfile) $(BOOTCFLAGS) -c -o $@ $<
@@ -339,7 +339,9 @@ install: $(CONFIGURE) $(addprefix $(obj)/, $(image-y))
 	sh -x $(srctree)/$(src)/install.sh "$(KERNELRELEASE)" vmlinux System.map "$(INSTALL_PATH)" $<
 
 # anything not in $(targets)
-clean-files += $(image-) $(initrd-) zImage zImage.initrd cuImage.* treeImage.* \
+clean-files += $(image-) $(initrd-) cuImage.* dtbImage.* treeImage.* \
+	zImage zImage.initrd zImage.chrp zImage.coff zImage.holly \
+	zImage.iseries zImage.miboot zImage.pmac zImage.pseries \
 	otheros.bld *.dtb
 
 # clean up files cached by wrapper