drm: adv7511: Fix low refresh rate register for ADV7533/5

For ADV7533 and ADV7535 low refresh rate is selected using
bits [3:2] of 0x4a main register.
So depending on ADV model write 0xfb or 0x4a register.

Fixes: 2437e7cd ("drm/bridge: adv7533: Initial support for ADV7533")
Reviewed-by: Robert Foss <rfoss@kernel.org>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Signed-off-by: Bogdan Togorean <bogdan.togorean@analog.com>
Signed-off-by: Alexandru Ardelean <alex@shruggie.ro>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230719060143.63649-1-alex@shruggie.ro

drivers/gpu/drm/bridge/adv7511/adv7511_drv.c

@@ -786,8 +786,13 @@ static void adv7511_mode_set(struct adv7511 *adv7511,
 	else
 		low_refresh_rate = ADV7511_LOW_REFRESH_RATE_NONE;
 
-	regmap_update_bits(adv7511->regmap, 0xfb,
-		0x6, low_refresh_rate << 1);
+	if (adv7511->type == ADV7511)
+		regmap_update_bits(adv7511->regmap, 0xfb,
+				   0x6, low_refresh_rate << 1);
+	else
+		regmap_update_bits(adv7511->regmap, 0x4a,
+				   0xc, low_refresh_rate << 2);
+
 	regmap_update_bits(adv7511->regmap, 0x17,
 		0x60, (vsync_polarity << 6) | (hsync_polarity << 5));