i2c-i801: Enable interrupts for all post-ICH5 chips

I did not receive a single bug report after interrupt support was
added for a limited number of chips. So I'd say the code is good and
should be enabled for all supported chips, that is: ICH5 and later.

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