mfd: wcd9xxx: Add support to parse new set of regulators

Chargepump supply to the codec can be supplied from multiple
regulators. Add support to maintain list of regulators for
chargepump that can be used by individual codec drivers to
dynamically enable/disable the regulators.

Change-Id: I22e2abac349f099ed60a786e50bc15cffd0a3aa2
Signed-off-by: Bhalchandra Gajare <gajare@codeaurora.org>