drm: bridge: adv7511: make adv7511_hdmi_hw_params() static

This eliminates the following sparse warning:

drivers/gpu/drm/bridge/adv7511/adv7511_audio.c:58:5: warning: symbol
'adv7511_hdmi_hw_params' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200912033826.142923-1-yanaijie@huawei.com

drivers/gpu/drm/bridge/adv7511/adv7511_audio.c

@@ -55,9 +55,9 @@ static int adv7511_update_cts_n(struct adv7511 *adv7511)
 	return 0;
 }
 
-int adv7511_hdmi_hw_params(struct device *dev, void *data,
-			   struct hdmi_codec_daifmt *fmt,
-			   struct hdmi_codec_params *hparms)
+static int adv7511_hdmi_hw_params(struct device *dev, void *data,
+				  struct hdmi_codec_daifmt *fmt,
+				  struct hdmi_codec_params *hparms)
 {
 	struct adv7511 *adv7511 = dev_get_drvdata(dev);
 	unsigned int audio_source, i2s_format = 0;