uec: add support for Broadcom BCM5481 Gigabit PHY

This patch adds basic support for Broadcom BCM5481 PHY.

RXD-RXC delay quirk comes from MPC8360E-RDK BSP source, author is
Peter Barada <peterb@logicpd.com>.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>