drm/amd/display: feed PSR-SU as psr version to dmub FW

[why & how]
set psr version as PSR-SU in kernel-FW interface function to ensure
the correct dmub command parameter is fed into FW.

Signed-off-by: David Zhang <dingchen.zhang@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>