drm/amd/display: Allow HPO PG for DCN35

[Why]
HPO can be power gated unconditionally for
DCN35.

[How]
Set disable flag to false.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Roman Li <roman.li@amd.com>
Signed-off-by: Duncan Ma <duncan.ma@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>