busybox/mdev-mount.sh: Fix partition detect and cleanup mountpoint on fail

This fixes issues mainly seen when mounting eMMC devices:

The wildcard /sys/block/${DEVBASE}/${DEVBASE}*1 matches both "mmcblk0p1"
and "mmcblk0boot1" for example, and this results in syntax errors. Fix this
by searching for a "partition" file instead, which only exists for real
partitions and not 'fakes' like the eMMC extra's.

When mount fails, the mountpoint file is left behind, causing later attempts
at auto-mounting it to fail. If mount fails, remove the mountpoint, leaving
the system in the state as it was before the mount attempt.

(From OE-Core rev: 8645c0419456c1bd3ae15a9a7dd2b2e9a960eaf4)

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/busybox/files/mdev-mount.sh

@@ -25,7 +25,7 @@ case "$ACTION" in
 		fi
 		# check for full-disk partition
 		if [ "${DEVBASE}" = "${MDEV}" ] ; then
-			if [ -d /sys/block/${DEVBASE}/${DEVBASE}*1 ] ; then
+			if [ -f /sys/block/${DEVBASE}/${DEVBASE}*1/partition ] ; then
 				# Partition detected, just quit
 				exit 0
 			fi
@@ -43,7 +43,7 @@ case "$ACTION" in
 		then
 			MOUNTPOINT="${MDEV_AUTOMOUNT_ROOT}/$MDEV"
 			mkdir -p "$MOUNTPOINT"
-			mount -t auto /dev/$MDEV "$MOUNTPOINT"
+			mount -t auto /dev/$MDEV "$MOUNTPOINT" || rmdir "$MOUNTPOINT"
 		fi
 		;;
 	remove)