kbuild: add ARCH=sparc32 target

Add 'sparc32' ARCH target to test all{yes,mod}config for 32-bit build.
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Makefile

@@ -204,6 +204,9 @@ ifeq ($(ARCH),x86_64)
 endif
 
 # Additional ARCH settings for sparc
+ifeq ($(ARCH),sparc32)
+       SRCARCH := sparc
+endif
 ifeq ($(ARCH),sparc64)
        SRCARCH := sparc
 endif