drm: adv7511: mark ADV7511_REG_EDID_READ_CTRL volatile

This register includes a counter which is decremented by the chip on I2C
failures. Also, it is reset when powering down.
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: NArchit Taneja <architt@codeaurora.org>

drivers/gpu/drm/i2c/adv7511.c

@@ -136,6 +136,7 @@ static bool adv7511_register_volatile(struct device *dev, unsigned int reg)
 	case ADV7511_REG_BKSV(3):
 	case ADV7511_REG_BKSV(4):
 	case ADV7511_REG_DDC_STATUS:
+	case ADV7511_REG_EDID_READ_CTRL:
 	case ADV7511_REG_BSTATUS(0):
 	case ADV7511_REG_BSTATUS(1):
 	case ADV7511_REG_CHIP_ID_HIGH: