drm/amdkfd: heavy-weight flush TLB after unmap

Need do a heavy-weight TLB flush to make sure we have no more dirty data
in the cache for the unmapped pages.

Define enum TLB_FLUSH_TYPE, add flush_type parameter to
amdgpu_amdkfd_flush_gpu_tlb_pasid.

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>