drm/amd/display: fix zstate allow interface to PMFW

drm/amd/display: fix zstate allow interface to PMFW

[Why]
psr_feature_enabled flag is dynamically updated, and sometimes when
zstate allow status is determined the flag has not been set to true yet
even on PSR enabled config, lid off/on is such a case, which will result
in zstate disabled even though PSR is supported.

[How]
Check the supported PSR version and the PSR disable status instead.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Eric Yang <Eric.Yang2@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>