ipack/devices/ipoctal: avoid re-enable RX two times.

RX is enabled when the tty port is open, so no need to do it in initialization
time: it can allow the device to receive characters but no TTY client is
listening to them.

It produced an infinite number of IRQ as RxFIFO is not read to clear that
IRQ in the device, so it is still pending.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>