Marvell/Drivers: MvGpioDxe: Introduce platform GPIO driver

Marvell Armada 7k/8k SoCs comprise integrated GPIO controllers,
one in AP806 and two in each south bridge hardware blocks.

This patch introduces support for them. The new driver implements
a generic EMBEDDED_GPIO protocol.

In order to ease description of used GPIO pins and controllers
of the Armada 7k8k platforms, add a common enum type.

Based on original work of Jing Hua <jinghua@marvell.com>.

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