drm/i915: Send GCP infoframes for deep color HDMI sinks

GCP infoframes are required to inform the HDMI sink about the color
depth.

Send the GCP infoframe whenever the sink supports any deep color modes
since such sinks must anyway be capable of receiving them. For sinks
that don't support deep color let's skip the GCP in case it might
confuse the sink, although HDMI 1.4 spec does say all sinks must be
capable of reciving them. In theory we could skip the GCP infoframe
for deep color sinks in 8bpc mode as well since sinks must fall back to
8bpc whenever GCP isn't received for some time.

BSpec says we should disable GCP after disabling the port, so do that as
well.

v2: s/intel_set_gcp_infoframe/intel_hdmi_set_gcp_infoframe/
    Rebased due to crtc->config changes

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[danvet: Resolve conflict with lack of chv phy patches and fixup typo
Chandra spotted.]
Reviewed-by: Chandra Konduru <Chandra.konduru@intel.com>
Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>