[POWERPC] ppc: Don't run prom_init_check for arch/ppc builds

arch/ppc doesn't have prom_init.o (anymore).
Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/Makefile

@@ -105,6 +105,9 @@ PHONY += systbl_chk
 systbl_chk: $(src)/systbl_chk.sh $(obj)/systbl_chk.i
 	$(call cmd,systbl_chk)
 
+
+ifeq ($(CONFIG_PPC_MERGE),y)
+
 $(obj)/built-in.o:		prom_init_check
 
 quiet_cmd_prom_init_check = CALL    $<
@@ -114,4 +117,7 @@ PHONY += prom_init_check
 prom_init_check: $(src)/prom_init_check.sh $(obj)/prom_init.o
 	$(call cmd,prom_init_check)
 
+endif
+
+
 clean-files := vmlinux.lds