drm/amdgpu:unmap KCQ in gfx hw_fini(v2)

v2:
move kcq_disable out of SRIOV, make it genearal

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>