at91_mci: minor cleanup

MMC_POWER_ON is a noop, no need to set the power pin again.
Signed-off-by: NMarc Pignat <marc.pignat@hevs.ch>
Signed-off-by: NPierre Ossman <drzeus@drzeus.cx>

drivers/mmc/host/at91_mci.c

@@ -663,9 +663,12 @@ static void at91_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 				gpio_set_value(host->board->vcc_pin, 0);
 				break;
 			case MMC_POWER_UP:
-			case MMC_POWER_ON:
 				gpio_set_value(host->board->vcc_pin, 1);
 				break;
+			case MMC_POWER_ON:
+				break;
+			default:
+				WARN_ON(1);
 		}
 	}
 }