[WATCHDOG] iTCO_wdt: Fix ICH7+ reboot issue.

[WATCHDOG] iTCO_wdt: Fix ICH7+ reboot issue.

Bugzilla: 9868 & 10195.
There seems to be a bug into the SMM code that handles TCO Timeout SMI.
Andriy Gapon found that the code on his DG33TL system does the following:
> The handler is quite simple - it tests value in TCO1_CNT against 0x800, i.e.
> checks TCO_TMR_HLT. If the bit is set the handler goes into an infinite loop,
> apparently to allow the second timeout and reboot. Otherwise it simply clears
> TIMEOUT bit in TCO1_STS and that's it.
> So the logic seems to be reversed, because it is hard to see how TIMEOUT can
> get set to 1 and SMI generated when TCO_TMR_HLT is set (other than a
> transitional effect).

The only trick we have is to bypass the SMM code by turning of the generation
of the SMI#. The trick can only be enabled by setting the vendorsupport module
parameter to 911. This trick doesn't work well on laptop's.

Note: this is a dirty hack. Please handle with care. The only real fix is that
the bug in the SMM bios code get's fixed.

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