net: socionext: Add Synquacer NetSec driver

This driver adds support for Socionext "netsec" IP Gigabit
Ethernet + PHY IP used in the Synquacer SC2A11 SoC.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>