drm/amdgpu: add SDMA v4.0 implementation (v2)

v2: fix Makefile

Signed-off-by: Ken Wang <Qingqing.Wang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/Makefile b/drivers/gpu/drm/amd/amdgpu/Makefile
index ccbc4c0..9c117d0 100644
--- a/drivers/gpu/drm/amd/amdgpu/Makefile
+++ b/drivers/gpu/drm/amd/amdgpu/Makefile
@@ -69,7 +69,8 @@
 # add async DMA block
 amdgpu-y += \
 	sdma_v2_4.o \
-	sdma_v3_0.o
+	sdma_v3_0.o \
+	sdma_v4_0.o
 
 # add UVD block
 amdgpu-y += \