regulator: qpnp-regulator: Add support for reading all possible voltages

Extend the voltage range configuration data so that it fully
describes all possible set point values for each regulator type
in addition to specifying which range to use in the case of
overlap.

Change-Id: Ifdef83720f1c9ef6f74e64ce27ec5e7e27ccba9f
Signed-off-by: David Collins <collinsd@codeaurora.org>