regulator: ab8500: Provide supply names for the AUX regulators

On some platforms the AUX[1|2|3] regulators are supplied voltage by
a separate regulator. For example on Snowball these are provided by
the EXT3. If we list them here, we can supply voltage to them by
simply listing them in as a consumer of EXT3 in the Snowball case.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonielinaro.org>