drm/amdgpu: Remove the unneeded result variable

Return the sdma_v6_0_start() directly instead of storing it in another
redundant variable.
Reported-by: NZeal Robot <zealci@zte.com.cn>
Signed-off-by: Nzhang songyi <zhang.songyi@zte.com.cn>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/sdma_v6_0.c

@@ -1377,12 +1377,9 @@ static int sdma_v6_0_sw_fini(void *handle)
 
 static int sdma_v6_0_hw_init(void *handle)
 {
-	int r;
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
-	r = sdma_v6_0_start(adev);
-
-	return r;
+	return sdma_v6_0_start(adev);
 }
 
 static int sdma_v6_0_hw_fini(void *handle)