drm/amdgpu: fix the missed handling for SDMA2 and SDMA3

There is no base reg offset or ip_version set for SDMA2
and SDMA3 on SIENNA_CICHLID, so add them.
Signed-off-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Kevin Wang <kevinyang.wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_discovery.c

@@ -157,6 +157,8 @@ static int hw_id_map[MAX_HWIP] = {
 	[HDP_HWIP]	= HDP_HWID,
 	[SDMA0_HWIP]	= SDMA0_HWID,
 	[SDMA1_HWIP]	= SDMA1_HWID,
+	[SDMA2_HWIP]    = SDMA2_HWID,
+	[SDMA3_HWIP]    = SDMA3_HWID,
 	[MMHUB_HWIP]	= MMHUB_HWID,
 	[ATHUB_HWIP]	= ATHUB_HWID,
 	[NBIO_HWIP]	= NBIF_HWID,