sh: Do not define -ffreestanding twice

-ffreestanding is defined at the top Makefile for all architectures.
Do not define it twice for SH2A.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>

arch/sh/cpu/sh2/config.mk

@@ -8,7 +8,7 @@
 ENDIANNESS += -EB
 
 ifdef CONFIG_SH2A
-PLATFORM_CPPFLAGS += -m2a -m2a-nofpu -mb -ffreestanding
+PLATFORM_CPPFLAGS += -m2a -m2a-nofpu -mb
 else # SH2
 PLATFORM_CPPFLAGS += -m3e -mb
 endif