m32r: use KBUILD_DEFCONFIG

With using KBUILD_DEFCONFIG we don't have to ship a second copy of
m32700ut.smp_defconfig

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Hirokazu Takata <takata@linux-m32r.org>

arch/m32r/Makefile

@@ -5,6 +5,8 @@
 # architecture-specific flags and dependencies.
 #
 
+KBUILD_DEFCONFIG := m32700ut.smp_defconfig
+
 LDFLAGS		:=
 OBJCOPYFLAGS	:= -O binary -R .note -R .comment -S
 LDFLAGS_vmlinux	:=