iwlwifi: bump firmware API for mvm devices to 12

[ Upstream commit 91f491fd7dfbae6e5ce5887293723d818adf7d5d ]

This allows 3160 / 7260 / 7265 / 7265D / 8000 devices to
use the latest version of the firmware.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>