drm/gma500: remove unnecessary config_enabled() guard

Commit d112a8163f83 ("gma500/cdv: Add eDP support") replaced the
code inside this if-conditional with gma_backlight_set(), which
becomes a nop stub if CONFIG_BACKLIGHT_CLASS_DEVICE is disabled.
So, there is no need to guard the caller with config_enabled().

Note:
This is one of remaining TODOs to deprecate config_enabled() macro.
Refer to commit 97f2645f358b ("tree-wide: replace config_enabled()
with IS_ENABLED()").

Signed-off-by: Masahiro Yamada <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: http://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/gma500/opregion.c

···
 	if (bclp > 255)
 		return ASLE_BACKLIGHT_FAILED;
 
-	if (config_enabled(CONFIG_BACKLIGHT_CLASS_DEVICE)) {
-		int max = bd->props.max_brightness;
-		gma_backlight_set(dev, bclp * max / 255);
-	}
+	gma_backlight_set(dev, bclp * bd->props.max_brightness / 255);
 
 	asle->cblv = (bclp * 0x64) / 0xff | ASLE_CBLV_VALID;