drm/amdgpu: wrap kiq ring ops with kiq spinlock

KIQ ring is being operated by kfd as well as amdgpu.
KFD is using kiq lock, we should the same from amdgpu side
as well.

Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>