iwlwifi: mvm: Fix calculation of frame length

The RADA might include in the Rx frame the MIC and CRC bytes.
These bytes should be removed for non monitor interfaces and
should not be passed to mac80211.

Fix the Rx processing to remove the extra bytes on non monitor
cases.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20211219121514.098be12c801e.I1d81733d8a75b84c3b20eb6e0d14ab3405ca6a86@changeid


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>