am335x, guardian: Enable backlight

Enable backlight, set brightness value and dimming frequency

Signed-off-by: Gireesh Hiremath <Gireesh.Hiremath@in.bosch.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20210611161350.2141-13-Gireesh.Hiremath@in.bosch.com
diff --git a/include/configs/am335x_guardian.h b/include/configs/am335x_guardian.h
index c76f9b2..7324829 100644
--- a/include/configs/am335x_guardian.h
+++ b/include/configs/am335x_guardian.h
@@ -59,6 +59,7 @@
 	BOOTENV \
 	GUARDIAN_DEFAULT_PROD_ENV \
 	"autoload=no\0" \
+	"backlight_brightness=50\0" \
 	"bootubivol=rootfs\0" \
 	"distro_bootcmd=" \
 		"setenv rootflags \"bulk_read,chk_data_crc\"; " \