i2c: i801: Restore INTREN on unload

If driver interrupts are enabled, SMBHSTCNT_INTREN will be 1 after
the first transaction, and will stay to that value forever. This
means that interrupts will be generated for both host-initiated
transactions and also SMBus Alert events even after the driver is
unloaded. To be on the safe side, we should restore the initial state
of this bit at suspend and reboot time, as we do for several other
configuration bits already and for the same reason: the BIOS should
be handed the device in the same configuration state in which we
received it. Otherwise interrupts may be generated which nobody
will process.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>