USB: serial: pl2303: add ids for Hewlett-Packard HP POS pole displays

Add device ids to pl2303 for the HP POS pole displays:
LM920:   03f0:026b
TD620:   03f0:0956
LD960TA: 03f0:4439
LD220TA: 03f0:4349
LM940:   03f0:5039

Signed-off-by: Scott Chen <scott@labau.com.tw>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>