USB: ark3116: add IrDA support for Gembird UIR-22

Add IrDA support to ark3116 driver.  This makes Gembird UIR-22 USB to IrDA
adapter work (vendor ID 0x18ec, device ID 0x3118).  This adapter contains
ARK3116T USB serial chip and an IrDA transceiver, thus a command like
"irattach /dev/ttyUSB0 -s" is needed.

All magic numbers were captured using usbsnoop from windows driver that
came with the device.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>