usb: serial/pl2303: support for IO Data Device RSAQ5

This patch adds support for the IO Data Device USB-RSAQ5, PL2303 based
USB-serial converter, to pl2303 driver

Signed-off-by: Masakazu Mokuno <mokuno@sm.sony.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>