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.

Signed-off-by: Dario Lombardo <dario.lombardo@libero.it>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>