hwmon/vt1211: Add probing of alternate config index port

The configuration index port of the vt1211 can be accessed at two
different addresses 0x2e or 0x4e, depending on pin strappings. This
patch adds support to scan both addresses during module
initialization.

Signed-off-by: Juerg Haefliger <juergh@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>