unicore32: add KBUILD_DEFCONFIG with unicore32_defconfig (old debug_defconfig)

Rename debug_defconfig to unicore32_defconfig, which is a minimal config for
PKUnity-v3 (130nm) SoC board.
Also, add KBUILD_DEFCONFIG to use 'make defconfig'.

Signed-off-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Acked-by: Arnd Bergmann <arnd@arndb.de>

arch/unicore32/Makefile

@@ -75,7 +75,8 @@ endif
 
 boot			:= arch/unicore32/boot
 
-# Default target when executing plain make
+# Default defconfig and target when executing plain make
+KBUILD_DEFCONFIG	:= $(ARCH)_defconfig
 KBUILD_IMAGE		:= zImage
 
 all:	$(KBUILD_IMAGE)

arch/unicore32/configs/debug_defconfig → arch/unicore32/configs/unicore32_defconfig

@@ -1,6 +1,6 @@
 ### General setup
 CONFIG_EXPERIMENTAL=y
-CONFIG_LOCALVERSION="-debug"
+CONFIG_LOCALVERSION="-unicore32"
 CONFIG_SWAP=y
 CONFIG_SYSVIPC=y
 CONFIG_POSIX_MQUEUE=y