iwlwifi: mvm: remove support for legacy power API

If the driver detects old firmware, we disable support for
power management.
This greatly simplifies the code.

Reviewed-by: Alexander Bondar <alexander.bondar@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/mvm/fw.c b/drivers/net/wireless/iwlwifi/mvm/fw.c
index 212ffec..155bb20 100644
--- a/drivers/net/wireless/iwlwifi/mvm/fw.c
+++ b/drivers/net/wireless/iwlwifi/mvm/fw.c
@@ -442,7 +442,13 @@
 	/* Initialize tx backoffs to the minimal possible */
 	iwl_mvm_tt_tx_backoff(mvm, 0);
 
-	ret = iwl_mvm_power_update_device_mode(mvm);
+	if (!(mvm->fw->ucode_capa.flags & IWL_UCODE_TLV_FLAGS_PM_CMD_SUPPORT)) {
+		ret = iwl_power_legacy_set_cam_mode(mvm);
+		if (ret)
+			goto error;
+	}
+
+	ret = iwl_mvm_power_update_device(mvm);
 	if (ret)
 		goto error;