drm/amd/display: Assume LTTPR interop for DCN31+

[WHY]
For DCN31 onward, LTTPR is to be enabled and set to Transparent by
VBIOS.  Driver is to assume that VBIOS has done this without needing to
check the VBIOS interop bit.

[HOW]
Add LTTPR enable and interop VBIOS bits into dc->caps, and force-set the
interop bit to true for DCN31+.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Wesley Chalmers <Wesley.Chalmers@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>