drm/amdgpu: Adjust usleep_range in fence wait

drm/amdgpu: Adjust usleep_range in fence wait

Tune the sleep interval in the PSP fence wait loop from 10-100us to
60-100us.This adjustment results in an overall wait window of 1.2s
(60us * 20000 iterations) to 2 seconds (100us * 20000 iterations),
which guarantees that we can retrieve the correct fence value

Signed-off-by: Ce Sun <cesun102@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>