drm/amd/powerplay: increase waiting time for smu response

We observed some SMU commands take more time for execution,
so increase waiting time for response.

Signed-off-by: Jack Xiao <Jack.Xiao@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>