Marvell/Armada7k8k: Extend ArmadaSoCDescLib with I2C information

This patch introduces new library callback (ArmadaSoCDescI2cGet ()),
which dynamically allocates and fills MV_SOC_I2C_DESC structure with
the SoC description of I2c controllers.

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