net: rfkill: Do not ignore errors from regulator_enable()

Function regulator_enable() may return an error that has to be checked.
This patch changes function rfkill_regulator_set_block() so that it checks
for the return code.  Also, rfkill_data->reg_enabled is set to 'true' only
if there is no error.

This fixes the following compilation warning:

net/rfkill/rfkill-regulator.c:43:20: warning: ignoring return value of 'regulator_enable', declared with attribute warn_unused_result [-Wunused-result]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/rfkill/rfkill-regulator.c

@@ -30,6 +30,7 @@ struct rfkill_regulator_data {
 static int rfkill_regulator_set_block(void *data, bool blocked)
 {
 	struct rfkill_regulator_data *rfkill_data = data;
+	int ret = 0;
 
 	pr_debug("%s: blocked: %d\n", __func__, blocked);
 
@@ -40,15 +41,16 @@ static int rfkill_regulator_set_block(void *data, bool blocked)
 		}
 	} else {
 		if (!rfkill_data->reg_enabled) {
-			regulator_enable(rfkill_data->vcc);
-			rfkill_data->reg_enabled = true;
+			ret = regulator_enable(rfkill_data->vcc);
+			if (!ret)
+				rfkill_data->reg_enabled = true;
 		}
 	}
 
 	pr_debug("%s: regulator_is_enabled after set_block: %d\n", __func__,
 		regulator_is_enabled(rfkill_data->vcc));
 
-	return 0;
+	return ret;
 }
 
 static struct rfkill_ops rfkill_regulator_ops = {