The nv05 card in the bug report [1] doesn't have usable I2C port
register offsets (they're all filled with zeros). Ignore them and use
the defaults.

[1] http://bugs.launchpad.net/bugs/569505Signed-off-by: NFrancisco Jerez <currojerez@riseup.net>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>