drm/i915/hdmi: Change the write_infoframe vfunc to take a buffer and a type

drm/i915/hdmi: Change the write_infoframe vfunc to take a buffer and a type

First step in the move to the shared infoframe infrastructure, let's
move the different infoframe helpers and the write_infoframe() vfunc to
a type (enum hdmi_infoframe_type) and a buffer + len instead of using
our struct dip_infoframe.

v2: constify the infoframe pointer and don't mix signs (Ville Syrjälä)

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
Signed-off-by: Thierry Reding <thierry.reding at avionic-design.de>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>