kbuild: use -fno-optimize-sibling-calls unconditionally

We don't have to check for -fno-optimize-sibling-calls since even
gcc 3.2 supports it.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

@@ -492,7 +492,7 @@ endif
 include $(srctree)/arch/$(ARCH)/Makefile
 
 ifdef CONFIG_FRAME_POINTER
-CFLAGS		+= -fno-omit-frame-pointer $(call cc-option,-fno-optimize-sibling-calls,)
+CFLAGS		+= -fno-omit-frame-pointer -fno-optimize-sibling-calls
 else
 CFLAGS		+= -fomit-frame-pointer
 endif