drm/amd/display: Retry getting PSR state if command times out

[Why]
GPINT command to get PSR state from FW times out.

[How]
Add retry to get valid PSR state.

Signed-off-by: Wyatt Wood <wyatt.wood@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>