drm/sun4i: Make some symbols static

Fix sparse warnings:

drivers/gpu/drm/sun4i/sun8i_tcon_top.c:271:36: warning: symbol 'sun8i_r40_tcon_top_quirks' was not declared. Should it be static?
drivers/gpu/drm/sun4i/sun8i_tcon_top.c:276:36: warning: symbol 'sun50i_h6_tcon_top_quirks' was not declared. Should it be static?
drivers/gpu/drm/sun4i/sun4i_tcon.c:239:6: warning: symbol 'sun4i_tcon_set_mux' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190416145855.20852-1-yuehaibing@huawei.com

drivers/gpu/drm/sun4i/sun4i_tcon.c

@@ -236,7 +236,7 @@ static struct sun4i_tcon *sun4i_get_tcon0(struct drm_device *drm)
 	return NULL;
 }
 
-void sun4i_tcon_set_mux(struct sun4i_tcon *tcon, int channel,
+static void sun4i_tcon_set_mux(struct sun4i_tcon *tcon, int channel,
 			       const struct drm_encoder *encoder)
 {
 	int ret = -ENOTSUPP;

drivers/gpu/drm/sun4i/sun8i_tcon_top.c

@@ -268,12 +268,12 @@ static int sun8i_tcon_top_remove(struct platform_device *pdev)
 	return 0;
 }
 
-const struct sun8i_tcon_top_quirks sun8i_r40_tcon_top_quirks = {
+static const struct sun8i_tcon_top_quirks sun8i_r40_tcon_top_quirks = {
 	.has_tcon_tv1	= true,
 	.has_dsi	= true,
 };
 
-const struct sun8i_tcon_top_quirks sun50i_h6_tcon_top_quirks = {
+static const struct sun8i_tcon_top_quirks sun50i_h6_tcon_top_quirks = {
 	/* Nothing special */
 };