Revert "USB: serial: add Moxa UPORT 11x0 driver"

This reverts commit 0b2b093a.

Turns out the MOXA vendor driver was basically just a copy of the
ti_usb_3410_5052 driver. We don't want two drivers for the same chip
even if mxu11x0 had gotten some much needed clean up before merge. So
let's remove the mxu11x0 driver, add support for these Moxa devices to
the TI driver, and then clean that driver up instead.

Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>