dt/i2c: Enumerate some of the known trivial i2c devices

Based on recent discussions, we apparently want to do bindings even for
trivial i2c devices, even though they have for years just been added. So
start a table of the currently known ones for others to be added to
over time.

(I am intentionally letting lines go over 80 characters to make it easier
to sort the file).

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>