ATI/AMD HDMI codecs do not include standard HDA HDMI HBR support (which
is required for bitstreaming DTS-HD and Dolby TrueHD), instead they have
custom verbs for checking and enabling it.

Add support for the ATI/AMD HDMI HBR verbs.

The specification is available at:
http://www.x.org/docs/AMD/AMD_HDA_verbs_v2.pdf

v2: adapted to hdmi_ops infrastructure
Signed-off-by: Anssi Hannula <anssi.hannula@iki.fi>
Tested-by: Peter Frühberger <fritsch@xbmc.org> # v1
Signed-off-by: Takashi Iwai <tiwai@suse.de>