xfs: Print XFS UUID on mount and umount events.

xfs: Print XFS UUID on mount and umount events.

As of now only device names are printed out over __xfs_printk().
The device names are not persistent across reboots which in case
of searching for origin of corruption brings another task to properly
identify the devices. This patch add XFS UUID upon every mount/umount
event which will make the identification much easier.

Signed-off-by: Lukas Herbolt <lukas@herbolt.com>
[sandeen: rebase onto current upstream kernel]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>