[Why]
The vendor specific infoframe is needed for HDMI while displaying
specific modes.
DC supports sending it, but we aren't currently building it
[How]
Add mod_build_hf_vsif_infopacket() to build the vendor specific
info packet.
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com> Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com> Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>