i2c-i801: Enable interrupts on ICH5/7/8/9/10

Enable interrupts on more devices. ICH5, ICH7(-M) and ICH10 have been
tested to work OK. ICH8 and ICH9 are expected to work just fine as
they are very close to ICH7 and ICH10.

Ultimately we want to enable this feature on at least every device
since the ICH5, but for now we limit the exposure. We'll enable it for
other devices if we don't get negative feedback.

As a bonus, let the user know when interrupts are used.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Daniel Kurtz <djkurtz@chromium.org>