[POWERPC] Remove generated files on make clean

vmlinux.lds and dtc-parser.tab.h get created but never cleaned up.
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/boot/Makefile

@@ -147,6 +147,8 @@ HOSTCFLAGS += -I$(src)/dtc-src/ -I$(src)/libfdt/
 targets += dtc-src/dtc-parser.tab.c
 targets += dtc-src/dtc-lexer.lex.c
 
+clean-files += dtc-src/dtc-parser.tab.h
+
 ifdef DTC_GENPARSER
 BISON = bison
 FLEX = flex

arch/powerpc/kernel/Makefile

@@ -104,3 +104,5 @@ quiet_cmd_systbl_chk = CALL    $<
 PHONY += systbl_chk
 systbl_chk: $(src)/systbl_chk.sh $(obj)/systbl_chk.i
 	$(call cmd,systbl_chk)
+
+clean-files := vmlinux.lds