drm/amdgpu/sriov add amdgpu_amdkfd_pre_reset in gpu reset

[PATCH 2/2]
kfd_pre_reset will free mem_objs allocated by kfd_gtt_sa_allocate

Without this change, sriov tdr code path will never free those
allocated memories and get memory leak.

Signed-off-by: Jack Zhang <Jack.Zhang1@amd.com>
Reviewed-by: Monk Liu <monk.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>