tty_driver->owner is not set, so if somebody remove mxser_module, it might
oops (and doesn't tell the user: no way, it's in use). Set the .owner value.

Cc: <osv@javad.com>
Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>