arm: marvell: Extract kirkwood gpio functions into new common file gpio.c

This makes is possible to use those gpio functions from other MVEBU SoC's as well.

Signed-off-by: Stefan Roese <sr@denx.de>
Tested-by: Luka Perkov <luka@openwrt.org>
Acked-by: Prafulla Wadaskar <prafulla@marvell.com>
24 files changed