platform_data/mlxreg: additions for Mellanox watchdog driver.

There are two new fields added to mlxreg core structure:
features - supported features of device and
identity - device identity name.
Add new defines for watchdog features.

Signed-off-by: Michael Shych <michaelsh@mellanox.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>