Makefile: simplify handling of build target names

Instead of stripping the "_config" part from the make target names in
each call of the "mkconfig" script let this script strip the string.

This prepares the ground for forther simplification of the top level
Makefile.

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/mkconfig b/mkconfig
index d3109e4..a71d09e 100755
--- a/mkconfig
+++ b/mkconfig
@@ -16,13 +16,13 @@
 	case "$1" in
 	--) shift ; break ;;
 	-a) shift ; APPEND=yes ;;
-	-n) shift ; BOARD_NAME="${1%%_config}" ; shift ;;
+	-n) shift ; BOARD_NAME="${1%_config}" ; shift ;;
 	-t) shift ; TARGETS="`echo $1 | sed 's:_: :g'` ${TARGETS}" ; shift ;;
 	*)  break ;;
 	esac
 done
 
-[ "${BOARD_NAME}" ] || BOARD_NAME="$1"
+[ "${BOARD_NAME}" ] || BOARD_NAME="${1%_config}"
 
 [ $# -lt 4 ] && exit 1
 [ $# -gt 6 ] && exit 1
@@ -102,7 +102,7 @@
 cat << EOF >> config.h
 #define CONFIG_BOARDDIR board/$BOARDDIR
 #include <config_defaults.h>
-#include <configs/$1.h>
+#include <configs/${BOARDNAME}.h>
 #include <asm/config.h>
 EOF