regulator: act8865: Remove unnecessary *rdev[] from struct act8865

Now we are using devm_regulator_register(), so we don't need the *rdev[] array
to store return value of devm_regulator_register. Use a *rdev variable is
enough for checking return status.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Wenyou Yang <Wenyou.yang@atmel.com>
Signed-off-by: Mark Brown <broonie@linaro.org>