i2c-sis5595: Resolve resource conflict with sis5595

Let the i2c-sis5595 driver release its PCI device after registering.
This is to allow the sis5595 hardware monitoring driver to also
access this PCI device. The same trick is already used in the
i2c-viapro and via686a drivers to let them both load.

Signed-off-by: Jean Delvare <khali@linux-fr.org>