s390/purgatory: remove duplicated build rule of kexec-purgatory.o

This is equivalent to the pattern rule in scripts/Makefile.build.

Having the dependency on $(obj)/purgatory.ro is enough.

Signed-off-by: Masahiro Yamada <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexander Gordeev <[email protected]>

Author: masahir0y

arch/s390/purgatory/Makefile

@@ -48,7 +48,6 @@ OBJCOPYFLAGS_purgatory.ro += --remove-section='.note.*'
 $(obj)/purgatory.ro: $(obj)/purgatory $(obj)/purgatory.chk FORCE
 		$(call if_changed,objcopy)
 
-$(obj)/kexec-purgatory.o: $(obj)/kexec-purgatory.S $(obj)/purgatory.ro FORCE
-	$(call if_changed_rule,as_o_S)
+$(obj)/kexec-purgatory.o: $(obj)/purgatory.ro
 
 obj-y += kexec-purgatory.o