sh: Use proper SH-2A CFLAGS on newer compilers.

-m2 doesn't end up working particularly well when we've got a constrained
toolchain target. Switch to the same semantics used by SH-4A to attempt
to get it right. Spotted by Alex Song <songqf9@yahoo.ca>.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/Makefile

@@ -35,6 +35,7 @@ endif
 endif
 
 cflags-$(CONFIG_CPU_SH2)		:= -m2
+cflags-$(CONFIG_CPU_SH2A)		:= -m2a $(call cc-option,-m2a-nofpu,)
 cflags-$(CONFIG_CPU_SH3)		:= -m3
 cflags-$(CONFIG_CPU_SH4)		:= -m4 \
 	$(call cc-option,-mno-implicit-fp,-m4-nofpu)