drm/nouveau/therm: use the EXTDEV table to detect i2c monitoring devices

This commit also adds a static list of all known devices and their possible
i2c addresses.

v2: use the common table parsing technique as suggested by darktama

Signed-off-by: Martin Peres <martin.peres@labri.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>