pda_power: Complain if regulator operations fail

Rather than silently ignoring errors from the regulator enable and disable
add a WARN_ON() - it's probably pretty important if we're not getting
power, though it should be vanishingly unlikely in production.
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NAnton Vorontsov <cbouatmailru@gmail.com>

drivers/power/pda_power.c

@@ -134,13 +134,13 @@ static void update_charger(void)
 			regulator_set_current_limit(ac_draw, max_uA, max_uA);
 			if (!regulator_enabled) {
 				dev_dbg(dev, "charger on (AC)\n");
-				regulator_enable(ac_draw);
+				WARN_ON(regulator_enable(ac_draw));
 				regulator_enabled = 1;
 			}
 		} else {
 			if (regulator_enabled) {
 				dev_dbg(dev, "charger off\n");
-				regulator_disable(ac_draw);
+				WARN_ON(regulator_disable(ac_draw));
 				regulator_enabled = 0;
 			}
 		}