kbuild: Trivial Makefile patch

The comment doesn't match the function name.

From: "Art Haas" <ahaas@airmail.net>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

@@ -290,7 +290,7 @@ check_gcc = $(warning check_gcc is deprecated - use cc-option) \
             $(call cc-option, $(1),$(2))
 
 # cc-option-yn
-# Usage: flag := $(call gcc-option-yn, -march=winchip-c6)
+# Usage: flag := $(call cc-option-yn, -march=winchip-c6)
 cc-option-yn = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
                 > /dev/null 2>&1; then echo "y"; else echo "n"; fi;)