i2c-i801: Cleanups

Various cleanups to the i2c-i801 driver:
* Fix documentation file and self file name references.
* i801_setup can be marked __devinit.
* Drop useless error local variable and label in i801_setup.
* Avoid a double PCI configuration register write in some cases.
* Use symbolic names for SMBHSTCFG bits.
* Transmit the error code returned by i801_setup instead of forcing it
  to an arbitrary value.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>