setup-keymap: allow specify the variant together with layout

Some users may know exactly which variant they want, and instead of
asking them two questions, we accept if users types in the variant at
the first question.

if the variant does not exist, then user is prompted.

setup-keymap.in

@@ -38,7 +38,13 @@ select_layout() {
 		default_read layout "$layout"
 		if [ "$layout" = "abort" ] || [ "$layout" = "none" ] ; then
 			goodbye 0
-		elif [ -d "$MAPDIR/$layout" ] ; then
+		fi
+		set -- $layout
+		if [ $# -eq 2 ]; then
+			layout="$1"
+			variant="$2"
+		fi
+		if [ -d "$MAPDIR/$layout" ] ; then
 			return 0
 		fi
 	done