drm/tinydrm: Call devres version of of_find_backlight

Call devm_of_find_backlight (the devres version) instead of
of_find_backlight.

Reviewed-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/244cd4d567cb3944a8cb7633715ffc8ac4e1ce83.1516810725.git.meghana.madhyastha@gmail.com
diff --git a/drivers/gpu/drm/tinydrm/st7735r.c b/drivers/gpu/drm/tinydrm/st7735r.c
index 2e6b7b8..67d197e 100644
--- a/drivers/gpu/drm/tinydrm/st7735r.c
+++ b/drivers/gpu/drm/tinydrm/st7735r.c
@@ -164,7 +164,7 @@ static int st7735r_probe(struct spi_device *spi)
 		return PTR_ERR(dc);
 	}
 
-	mipi->backlight = of_find_backlight(dev);
+	mipi->backlight = devm_of_find_backlight(dev);
 	if (IS_ERR(mipi->backlight))
 		return PTR_ERR(mipi->backlight);