drivers: update to pl2303 usb-serial to support Motorola cables
Added 0x0307 device id to support Motorola cables to the pl2303 usb
serial driver. This cable has a modified chip that is a pl2303, but
declares itself as 0307. Fixed by adding the right device id to the
supported devices list, assigning it the code labeled
PL2303_PRODUCT_ID_MOTOROLA.