x86: do not use $(ARCH) when not needed

For x86 ARCH may say i386 or x86_64 and soon x86.
Rely on CONFIG_X64_32 to select between 32/64 or just
hardcode the value as appropriate.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>

arch/x86/boot/Makefile

@@ -49,10 +49,10 @@ HOSTCFLAGS_build.o := $(LINUXINCLUDE)
 
 # How to compile the 16-bit code.  Note we always compile for -march=i386,
 # that way we can complain to the user if the CPU is insufficient.
-cflags-i386   := 
-cflags-x86_64 := -m32
+cflags-$(CONFIG_X86_32) :=
+cflags-$(CONFIG_X86_64) := -m32
 KBUILD_CFLAGS	:= $(LINUXINCLUDE) -g -Os -D_SETUP -D__KERNEL__ \
-		   $(cflags-$(ARCH)) \
+		   $(cflags-y) \
 		   -Wall -Wstrict-prototypes \
 		   -march=i386 -mregparm=3 \
 		   -include $(srctree)/$(src)/code16gcc.h \