net: wan: wanxl: use $(M68KCC) instead of $(M68KAS) for rebuilding firmware

The firmware source, wanxlfw.S, is currently compiled by the combo of
$(CPP) and $(M68KAS). This is not what we usually do for compiling *.S
files. In fact, this Makefile is the only user of $(AS) in the kernel
build.

Instead of combining $(CPP) and (AS) from different tool sets, using
$(M68KCC) as an assembler driver is simpler, and saner.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

drivers/net/wan/Makefile

@@ -40,16 +40,16 @@ $(obj)/wanxl.o:	$(obj)/wanxlfw.inc
 
 ifeq ($(CONFIG_WANXL_BUILD_FIRMWARE),y)
 ifeq ($(ARCH),m68k)
-  M68KAS = $(AS)
+  M68KCC = $(CC)
   M68KLD = $(LD)
 else
-  M68KAS = $(CROSS_COMPILE_M68K)as
+  M68KCC = $(CROSS_COMPILE_M68K)gcc
   M68KLD = $(CROSS_COMPILE_M68K)ld
 endif
 
 quiet_cmd_build_wanxlfw = BLD FW  $@
       cmd_build_wanxlfw = \
-	$(CPP) -D__ASSEMBLY__ -Wp,-MD,$(depfile) -I$(srctree)/include/uapi $< | $(M68KAS) -m68360 -o $(obj)/wanxlfw.o; \
+	$(M68KCC) -D__ASSEMBLY__ -Wp,-MD,$(depfile) -I$(srctree)/include/uapi -c -o $(obj)/wanxlfw.o $<; \
 	$(M68KLD) --oformat binary -Ttext 0x1000 $(obj)/wanxlfw.o -o $(obj)/wanxlfw.bin; \
 	hexdump -ve '"\n" 16/1 "0x%02X,"' $(obj)/wanxlfw.bin | sed 's/0x  ,//g;1s/^/static const u8 firmware[]={/;$$s/,$$/\n};\n/' >$(obj)/wanxlfw.inc; \
 	rm -f $(obj)/wanxlfw.bin $(obj)/wanxlfw.o