Marvell/Library: ComPhyLib: Switch library to use MARVELL_BOARD_DESC

MvComPhyLib library used to get Armada7k8k SerDes multiplexing
controller description from hardcoded values stored in the header
file MvHwDescLib.h. As a result it is very hard to support other
Armada SoC families with this library.

This patch updates the library, so that it can obtain the
description from newly introduced MARVELL_BOARD_DESC protocol,
and removes the dependency on the hardcoded structures.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Marcin Wojtas <mw@semihalf.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>