logfs: fix a leak in get_sb

a) switch ->put_device() to logfs_super *
b) actually call it on early failures in logfs_get_sb_device()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --cc fs/logfs/dev_bdev.c
Simple merge

diff --cc fs/logfs/dev_mtd.c
Simple merge

diff --cc fs/logfs/logfs.h
Simple merge

diff --cc fs/logfs/super.c
Simple merge