iwlwifi: distinguish different RF modules in A000 devices

iwlwifi: distinguish different RF modules in A000 devices

Newer versions of A000 devices come with two diffenent RF modules.
The PCI_ID, the subsystem ID and the RF ID are identical in these two cases,
so we need to differentiate them by using the CSR_HW_RF_ID register-
in order to load the appropriate firmware.

Signed-off-by: Tzipi Peres <tzipi.peres@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>