drivers/phy: marvell: Add support for the slave CP COMPHY device

With the support for the Armada 8k, a 2nd COMPHY controller now needs
to get supported from the CP110 slave controller. This patch adds support
for this 2nd contoller in the COMPHY driver.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Nadav Haklai <nadavh@marvell.com>
Cc: Neta Zur Hershkovits <neta@marvell.com>
Cc: Kostya Porotchkin <kostap@marvell.com>
Cc: Omri Itach <omrii@marvell.com>
Cc: Igal Liberman <igall@marvell.com>
Cc: Haim Boot <hayim@marvell.com>
Cc: Hanna Hawa <hannah@marvell.com>