kbuild: use assignment instead of define ... endef for filechk_* rules

You do not have to use define ... endef for filechk_* rules.

For simple cases, the use of assignment looks cleaner, IMHO.

I updated the usage for scripts/Kbuild.include in case somebody
misunderstands the 'define ... endif' is the requirement.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/Kbuild b/Kbuild
index 06b801e..65db5be 100644
--- a/Kbuild
+++ b/Kbuild
@@ -26,9 +26,7 @@
 
 targets += $(timeconst-file)
 
-define filechk_gentimeconst
-	echo $(CONFIG_HZ) | bc -q $<
-endef
+filechk_gentimeconst = echo $(CONFIG_HZ) | bc -q $<
 
 $(timeconst-file): kernel/time/timeconst.bc FORCE
 	$(call filechk,gentimeconst)