usb/serial: fix function args warnings, dropping *filp

Fix build warnings caused by removal of *filp arg in struct
usb_serial_driver.

These changes were missed somehow in commits 00a0d0d6 ("tty: remove
filp from the USB tty ioctls") and 60b33c13 ("tiocmget: kill off
the passing of the struct file")

  drivers/usb/serial/mct_u232.c:159: warning: initialization from incompatible pointer type
  drivers/usb/serial/opticon.c:627: warning: initialization from incompatible pointer type

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>