regulator: cpr3-regulator: support multiple regulators per CPR thread

Refactor the cpr3-regulator driver in order to add support for
multiple Linux regulator devices per CPR3 hardware thread.  This
ensures that optimal aggregation is possible between different
clock consumers of a single CPR3 thread.

Change-Id: I6511a91a9506121e0e15877c36c1b15c4b13cd57
Signed-off-by: David Collins <collinsd@codeaurora.org>