Marvell/Drivers: MvBoardDesc: Extend protocol with GPIO support

Introduce new callback that can provide information
about GPIO SoC controllers, as well as on-board
I2C IO expanders. According ArmadaSoCDescLib
ArmadaBoardDescLib routines are used for
obtaining required data.

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