net: phy: ca_phy: Add driver for CAxxxx SoCs

Add phy driver support for MACs embedded inside Cortina Access SoCs

Signed-off-by: Abbie Chang <abbie.chang@cortina-access.com>
Signed-off-by: Alex Nemirovsky <alex.nemirovsky@cortina-access.com>

CC: Joe Hershberger <joe.hershberger@ni.com>
CC: Tom Rini <trini@konsulko.com>
CC: Aaron Tseng <aaron.tseng@cortina-access.com>

Moved out PHY specific code out of Cortina NI Ethernet driver
and into a Cortina Access PHY interface driver