Makefile: "make kernelrelease" should show the correct full kernel version

After commit 85a256d8, 'make kernelrelease'
doesn't show the correct full kernel version. This patch fixes it,
'make kernelrelease' will show the same version name with the one
you finally get.

Cc: David Rientjes <rientjes@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Amerigo Wang <amwang@redhat.com>
[mmarek: merged with 09155120 and added dependency on
include/config/kernel.release]
Signed-off-by: Michal Marek <mmarek@suse.cz>

Makefile

@@ -414,7 +414,7 @@ endif
 no-dot-config-targets := clean mrproper distclean \
 			 cscope TAGS tags help %docs check% \
 			 include/linux/version.h headers_% \
-			 kernelrelease kernelversion
+			 kernelversion
 
 config-targets := 0
 mixed-targets  := 0
@@ -1395,9 +1395,9 @@ checkstack:
 	$(OBJDUMP) -d vmlinux $$(find . -name '*.ko') | \
 	$(PERL) $(src)/scripts/checkstack.pl $(CHECKSTACK_ARCH)
 
-kernelrelease:
-	$(if $(wildcard include/config/kernel.release), $(Q)echo $(KERNELRELEASE), \
-	$(error kernelrelease not valid - run 'make prepare' to update it))
+kernelrelease: include/config/kernel.release
+	@echo $(KERNELRELEASE)
+
 kernelversion:
 	@echo $(KERNELVERSION)