drm/amd/pm: avoid false alarm due to confusing softwareshutdowntemp setting

Normally softwareshutdowntemp should be greater than Thotspotlimit.
However, on some VEGA10 ASIC, the softwareshutdowntemp is 91C while
Thotspotlimit is 105C. This seems not right and may trigger some
false alarms.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>