make find_mtd_part work without devfs

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@6466 3c298f89-4303-0410-b956-a3cf2f4a3e73

package/base-files/files/etc/functions.sh

@@ -151,9 +151,11 @@ include() {
 
 find_mtd_part() {
 	local PART="$(grep "\"$1\"" /proc/mtd | awk -F: '{print $1}')"
+	local PREFIX=/dev/mtdblock
 	
 	PART="${PART##mtd}"
-	echo "${PART:+/dev/mtdblock/$PART}"
+	[ -d /dev/mtdblock ] && PREFIX=/dev/mtdblock/
+	echo "${PART:+$PREFIX$PART}"
 }
 
 strtok() { # <string> { <variable> [<separator>] ... }