drm/amd/powerplay: grant Arcturus softmin/max setting on latest PM firmware

For Arcturus, the softmin/max settings from driver are permitted on the
latest(54.26 later) SMU firmware. Thus enabling them in driver.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>