phy: marvell: save comphy_map_data priv structure

This allows the lower level driver access to comphy map data
(required for RX training support, which is introduced
in the following patches).

Change-Id: Ib7ffdc4b32076c01c3a5d33f59552c9dfc6b12fa
Signed-off-by: Igal Liberman <igall@marvell.com>