When mount is given a full path (including /dev/) to the cdev file
we can no longer automatically detect the filesystem. This is broken
since:
e89f1a1 detect_fs: use device instead of file
Fix it by dropping the /dev/ component of the path.
Signed-off-by: Peter Mamonov <pmamonov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>