iwlwifi: mvm: fix imbalanced locking in iwl_mvm_start_get_nvm()

If iwl_transt_start_hw() failed, we were returning without calling
wiphy_unlock() and rtnl_unlock(), causing a locking imbalance:

drivers/net/wireless/intel/iwlwifi/mvm/ops.c:686:12: warning: context imbalance in 'iwl_mvm_start_get_nvm' - wrong count at exit

Fix that by adding the unlock calls.
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20211219090128.42417-2-luca@coelho.fi

drivers/net/wireless/intel/iwlwifi/mvm/ops.c

@@ -718,6 +718,8 @@ static int iwl_mvm_start_get_nvm(struct iwl_mvm *mvm)
 	ret = iwl_trans_start_hw(mvm->trans);
 	if (ret) {
 		mutex_unlock(&mvm->mutex);
+		wiphy_unlock(mvm->hw->wiphy);
+		rtnl_unlock();
 		return ret;
 	}