[WATCHDOG] iTCO_wdt (Intel TCO Timer) driver

Hardware driver for the intel TCO timer based watchdog devices.
These drivers are included in the Intel 82801 I/O Controller
Hub family (from ICH0 up to ICH7) and in the Intel 6300ESB
controller hub.

This driver will replace the i8xx_tco.c driver.

Signed-off-by: Wim Van Sebroeck <wim@iguana.be>