mkconfig: pass the board name to board config file

Then we can handle different config targets in the board file, which
simplifies the top level Makefile for boards that have multiple
config targets.
Signed-off-by: NMingkai Hu <Mingkai.hu@freescale.com>

mkconfig

@@ -82,6 +82,7 @@ else
 	> config.h		# Create new config file
 fi
 echo "/* Automatically generated - do not edit */" >>config.h
+echo "#define CONFIG_MK_${BOARD_NAME} 1" >>config.h
 echo "#include <configs/$1.h>" >>config.h
 echo "#include <asm/config.h>" >>config.h