i2c: i801: Adding Intel Lewisburg support for iTCO

Starting from Intel Sunrisepoint (Skylake PCH) the iTCO watchdog
resources have been moved to reside under the i801 SMBus host
controller whereas previously they were under the LPC device.

This patch adds Intel lewisburg SMBus support for iTCO device.
It allows to load watchdog dynamically when the hardware is
present.

Fixes: cdc5a311 ("i2c: i801: add Intel Lewisburg device IDs")
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Alexandra Yates <alexandra.yates@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org