drm/amdgpu: fix uninitialized scalar variable warning

Clear warning that uses uninitialized value fw_size.
Signed-off-by: Tim Huang <Tim.Huang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1206,7 +1206,8 @@ void amdgpu_gfx_cp_init_microcode(struct amdgpu_device *adev,
 		fw_size = le32_to_cpu(cp_hdr_v2_0->data_size_bytes);
 		break;
 	default:
-		break;
+		dev_err(adev->dev, "Invalid ucode id %u\n", ucode_id);
+		return;
 	}
 
 	if (adev->firmware.load_type == AMDGPU_FW_LOAD_PSP) {