USB: serial: option: add u-blox LARA-R6 00B modem

The official LARA-R6 (00B) modem uses 0x908b PID. LARA-R6 00B does not
implement a QMI interface on port 4, the reservation (RSVD(4)) has been
added to meet other companies that implement QMI on that interface.

LARA-R6 00B USB composition exposes the following interfaces:
If 0: Diagnostic
If 1: AT parser
If 2: AT parser
If 3: AT parser/alternative functions

Signed-off-by: Davide Tronchin <davide.tronchin.94@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>