drm/i915/lspcon: Do not send DRM infoframes to non-HDMI sinks

Non-HDMI sinks shouldn't be sent Dynamic Range and Mastering infoframes.
Check for that when using LSPCON.

v2: Addressed Ville's review comment.

Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201130204738.2443-15-uma.shankar@intel.com