media: i2c: adv748x: Conditionally enable only CSI-2 outputs

The ADV748x has two CSI-2 output port and one TTL input/output port for
digital video reception/transmission. The TTL digital pad is unconditionally
enabled during the device reset even if not used. Same goes for the TXA
and TXB CSI-2 outputs, which are enabled by the initial settings blob
programmed into the chip.

In order to improve power saving, do not enable unused output interfaces:
keep TTL output disabled, as it is not used, and drop CSI-2 output enabling
from the initial settings list, as they get conditionally enabled later.

Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>