phy: marvell: Remove unused function comphy_update_map()

This weak function is not used anymore, so completely remove it.

Private struct comphy_map is not used by any board code anymore, so move it
into private driver header file comphy_core.h.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>