drm/i2c: tda998x: only configure infoframes and audio if supported

The CEA 861B specification indicates the situations when we are able to
send each infoframe based on the version of the EDID's CEA extension.
Update the tda998x driver to follow the CEA specification wrt sending
of infoframes.

Since we only support the generation of AVI version 2, this limits us
to CEA extension version 3, so we treat CEA extension version 2 as
CEA 861 (no infoframes, no audio.)

Tested-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Jon Medhurst <tixy@linaro.org>
Acked-by: Jon Medhurst <tixy@linaro.org>
Tested-by: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>