drm/amd: Make SDMA firmware load failures less noisy.

When firmware is missing we get failures at every step.
```
[    3.855086] amdgpu 0000:04:00.0: Direct firmware load for amdgpu/green_sardine_sdma.bin failed with error -2
[    3.855087] [drm:amdgpu_sdma_init_microcode [amdgpu]] *ERROR* SDMA: Failed to init firmware "amdgpu/green_sardine_sdma.bin"
[    3.855398] [drm:sdma_v4_0_early_init [amdgpu]] *ERROR* Failed to load sdma firmware!
```
Realistically we don't need all of these, a user can tell from the first one
that request_firmware emitted what happened. Drop the others.
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -280,10 +280,8 @@ int amdgpu_sdma_init_microcode(struct amdgpu_device *adev,
 	}
 
 out:
-	if (err) {
-		DRM_ERROR("SDMA: Failed to init firmware \"%s\"\n", fw_name);
+	if (err)
 		amdgpu_sdma_destroy_inst_ctx(adev, duplicate);
-	}
 	return err;
 }