watchdog: iTCO_wdt.c - problems with newer hardware due to SMI clearing (part 2)

Redhat Bugzilla: Bug 727875 - TCO_EN bit is disabled by TCO driver

The previous patch breaks reset watchdog behaviour on the older hardware.
It is therefor better to make sure that the behaviour for older hardware (<=ICH5 or
6300ESB) is preserved and that the behaviour for newer hardware is changed.
We therefor use the iTCO_version to see if we need the clearing of the SMI_TCO_EN
bit in the SMI_EN register.

So the new behaviour becomes:
turn_SMI_watchdog_clear_off=0 -> Do not turn off SMI clearing watchdog.
turn_SMI_watchdog_clear_off=1 -> Turn off SMI clearing watchdog when iTCO_version=1
				 (ICHO till ICH5 + 6300ESB only)
turn_SMI_watchdog_clear_off=2 -> Turn off SMI clearing watchdog.

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