leds: sgm3140: Add missing timer cleanup and flash gpio control

Enabling strobe and then setting brightness to 0 causes the driver to enter
invalid state after strobe end timer fires. We should cancel strobe mode
resources when changing brightness (aka torch mode).

Fixes: cef8ec8cbd21 ("leds: add sgm3140 driver")
Signed-off-by: Ondrej Jirman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

drivers/leds/flash/leds-sgm3140.c

···
 				"failed to enable regulator: %d\n", ret);
 			return ret;
 		}
+		gpiod_set_value_cansleep(priv->flash_gpio, 0);
 		gpiod_set_value_cansleep(priv->enable_gpio, 1);
 	} else {
+		del_timer_sync(&priv->powerdown_timer);
+		gpiod_set_value_cansleep(priv->flash_gpio, 0);
 		gpiod_set_value_cansleep(priv->enable_gpio, 0);
 		ret = regulator_disable(priv->vin_regulator);
 		if (ret) {