iwlwifi: return op_mode only in case the failure is from MEI

iwlwifi: return op_mode only in case the failure is from MEI

Currently we always return the op_mode with valid pointer in case
getting NVM failed, while it's only relevant for cases that CSME is the
owner of the nic.

Fix this by checking also who's the owner of the nic.

Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20211219132536.b1e96021b616.Id0164855f2dd01ecdecf79b239d6ee5974882245@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>