usb serial: Eliminate bogus ioctl code

Several drivers have bogus ioctl code that tries unneccessarily to
override the standard processing. In the three cases here the actual code
is not only wrong but also not required as they implement the proper
set_termios method as well.

Remove the junk.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>