i2c: i801: Convert to struct dev_pm_ops for suspend/resume

Stop using legacy PCI PM support and convert to standard dev_pm_ops.
This provides more straightforward path to add runtime PM.

While at it remove explicit PCI power state control and configuration space
save/restore as the PCI core does it.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>