kbuild: drop FORCE from PHONY targets

These targets are marked as PHONY.  No need to add FORCE to their
dependency.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
diff --git a/arch/ia64/Makefile b/arch/ia64/Makefile
index 970d0bd..648f1ce 100644
--- a/arch/ia64/Makefile
+++ b/arch/ia64/Makefile
@@ -95,8 +95,8 @@
   echo '* unwcheck	- Check vmlinux for invalid unwind info'
 endef
 
-archprepare: make_nr_irqs_h FORCE
+archprepare: make_nr_irqs_h
 PHONY += make_nr_irqs_h FORCE
 
-make_nr_irqs_h: FORCE
+make_nr_irqs_h:
 	$(Q)$(MAKE) $(build)=arch/ia64/kernel include/generated/nr-irqs.h