drm/amd: Use `amdgpu_ucode_release` helper for DMUB

The `amdgpu_ucode_release` helper is for symmetry on unloading.
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -1900,8 +1900,7 @@ static int load_dmcu_fw(struct amdgpu_device *adev)
 	if (r) {
 		dev_err(adev->dev, "amdgpu_dm: Can't validate firmware \"%s\"\n",
 			fw_name_dmcu);
-		release_firmware(adev->dm.fw_dmcu);
-		adev->dm.fw_dmcu = NULL;
+		amdgpu_ucode_release(&adev->dm.fw_dmcu);
 		return r;
 	}
 
@@ -2117,11 +2116,8 @@ static int dm_sw_fini(void *handle)
 		adev->dm.dmub_srv = NULL;
 	}
 
-	release_firmware(adev->dm.dmub_fw);
-	adev->dm.dmub_fw = NULL;
-
-	release_firmware(adev->dm.fw_dmcu);
-	adev->dm.fw_dmcu = NULL;
+	amdgpu_ucode_release(&adev->dm.dmub_fw);
+	amdgpu_ucode_release(&adev->dm.fw_dmcu);
 
 	return 0;
 }