hwmon: (abituguru) Depend on DMI

The abituguru drivers are only built on X86, where DMI support is now
enabled by default. So let these drivers depend on DMI, for the
following gains:
* Robustness and safety. Detection of these devices is weak and uses
  non-standard methods, it should really be limited to Abit boards
  unless the user explicitly asks otherwise.
* Code simplicity. The code is easier to read without ifdefs.
* Better build testing coverage. Now there's only one way to build the
  drivers, so no risk of build failure on exotic systems.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Alistair John Strachan <alistair@devzero.co.uk>
Acked-by: Hans de Goede <hdegoede@redhat.com>