orion_wdt: Support for the Orion Watchdog

The Orion watchdog can be found on some Marvell Armada chips.

This driver is based on the code by Tomas Hlavacek in the CZ.NIC
turris-omnia-uboot repository, which can be found at
https://gitlab.labs.nic.cz/turris/turris-omnia-uboot

, and that
one is based on code by Sylver Bruneau. His code is already in
mainline Linux kernel.

The code uses the new driver model API.

Signed-off-by: Tomas Hlavacek <tomas.hlavacek@nic.cz>
Signed-off-by: Marek Behun <marek.behun@nic.cz>

 create mode 100644 drivers/watchdog/orion_wdt.c
Signed-off-by: Stefan Roese <sr@denx.de>