i2c-i801: Better pci subsystem integration

Integrate the i2c-i801 driver better with the pci subsystem, by
calling pci_{enable,disable}_device and requesting the I/O region
by BAR rather than direct configuration space access.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>