iwlwifi: add GNSS differentiation to the device tables

Devices that also include a GNSS module have different names, so add a
new device option to differentiate them, according to the values we
have in the modules section of the subsystem device ID.

Additionally, convert the two applicable devices to use this value
instead of hardcoded subsystem IDs.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20200309091348.1f958e558d05.I45492bb57cbbeb4cc0ec84313bade4def7377a27@changeid