enetc: fix le32/le16 degrading to integer warnings

Fix blow sparse warning introduced by a previous patch.
- restricted __le32 degrades to integer
- restricted __le16 degrades to integer

Fixes: d3982312 ("enetc: add hardware timestamping support")
Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>