drm/amdgpu/psp: Update waiting in psp mode1 reset.

No point in use mdelay unless running from interrupt context (which we are not)
This is busy wait which will block the CPU for the entirety of the wait time.
Also, reduce wait time to 500ms as it is done in refernce code because
1s might cause PSP FW TO issues during XGMI hive reset.

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>