[PATCH] Char: mxser, fix oops when removing opened

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: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>