drm/amd/powerplay: unload mp1 for Arcturus RAS baco reset

This sequence is recommended by PMFW team for the baco reset
with PMFW reloaded. And it seems able to address the random
failure seen on Arcturus.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Reviewed-by: John Clements <John.Clements@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>