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: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Archit Taneja <architt@codeaurora.org>
1 file changed