ufs: implement show_options

An implementation of show_options method for UFS.

Signed-off-by: Evgeniy Dushistov <dushistov@mail.ru>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>