defconfig: lahaina-gki: enable the regulator proxy consumer library

Enable the regulator proxy consumer library so that proxy
consumer requests defined in device tree can be enforced at
runtime immediately after a given regulator is registered.

Change-Id: I1fe26c40521c1e7b9bf6dfc2d15119f6d9210355
Signed-off-by: David Collins <collinsd@codeaurora.org>