drm/connector: hdmi: Create Infoframe DebugFS entries

drm/connector: hdmi: Create Infoframe DebugFS entries

There has been some discussions recently about the infoframes sent by
drivers and if they were properly generated.

In parallel, there's been some interest in creating an infoframe-decode
tool similar to edid-decode.

Both would be much easier if we were to expose the infoframes programmed
in the hardware. It won't be perfect since we have no guarantee that
it's actually what goes through the wire, but it's the best we can do.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240527-kms-hdmi-connector-state-v15-24-c5af16c3aae2@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>