drm/amdkfd: KFD doesn't support TONGA SRIOV

KFD module doesn't support TONGA SRIOV, if init KFD module in TONGA SRIOV
environment, it will let compute ring IB test fail.

Signed-off-by: Emily Deng <Emily.Deng@amd.com>
Reviewed-by: Shaoyun.liu <Shaoyun.liu@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>