ia64: remove redundant 'export AWK'

This is exported by the top Makefile.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

arch/ia64/Makefile

@@ -16,8 +16,6 @@ KBUILD_DEFCONFIG := generic_defconfig
 NM := $(CROSS_COMPILE)nm -B
 READELF := $(CROSS_COMPILE)readelf
 
-export AWK
-
 CHECKFLAGS	+= -D__ia64=1 -D__ia64__=1 -D_LP64 -D__LP64__
 
 OBJCOPYFLAGS	:= --strip-all