arm64: mvebu: Init COMPHY from the slave-CP on the A8k

The Armada8k implements 2 CPs (communication processors) and the 2nd
CP also is equipped with a COMPHY controller. This patch now loops
over all enabled MISC devices (CP110) enabled in the DT to initialize
all CPs.

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>