drm/udl: Add missing static storage class specifiers in udl_fb.c

Fixes the following sparse warnings:
drivers/gpu/drm/udl/udl_fb.c:360:6: warning:
symbol 'udl_crtc_fb_gamma_set' was not declared. Should it be static?
drivers/gpu/drm/udl/udl_fb.c:365:6: warning:
symbol 'udl_crtc_fb_gamma_get' was not declared. Should it be static?

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/udl/udl_fb.c

@@ -357,12 +357,12 @@ static struct fb_ops udlfb_ops = {
 	.fb_release = udl_fb_release,
 };
 
-void udl_crtc_fb_gamma_set(struct drm_crtc *crtc, u16 red, u16 green,
+static void udl_crtc_fb_gamma_set(struct drm_crtc *crtc, u16 red, u16 green,
 			   u16 blue, int regno)
 {
 }
 
-void udl_crtc_fb_gamma_get(struct drm_crtc *crtc, u16 *red, u16 *green,
+static void udl_crtc_fb_gamma_get(struct drm_crtc *crtc, u16 *red, u16 *green,
 			     u16 *blue, int regno)
 {
 	*red = 0;