backlight: lp8788: staticize 'default_bl_config'

Fix the following sparse warning:

  drivers/video/backlight/lp8788_bl.c:55:25: warning: symbol 'default_bl_config' was not declared. Should it be static?
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/backlight/lp8788_bl.c

@@ -52,7 +52,7 @@ struct lp8788_bl {
 	struct pwm_device *pwm;
 };
 
-struct lp8788_bl_config default_bl_config = {
+static struct lp8788_bl_config default_bl_config = {
 	.bl_mode    = LP8788_BL_REGISTER_ONLY,
 	.dim_mode   = LP8788_DIM_EXPONENTIAL,
 	.full_scale = LP8788_FULLSCALE_1900uA,