net: phy: realtek: Introduce quirk to mark RXC not stoppable

net: phy: realtek: Introduce quirk to mark RXC not stoppable

When EEE is supported by the PHY and the driver allows it, libphy in the
kernel is configuring the PHY to stop receiving the xMII clock while it
is signaling LPI. While this (usually) works fine in the kernel this is
causing issues in U-Boot when rebooting from the linux kernel with this
bit set (without having the possibility to reset the PHY) where the PHY
suddenly stops working.

A new quirk is introduced to unconditionally reset this bit. If the
quirk is not enabled using the proper configuration symbol, the PHY state
is not changed.

Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>