regulator: core: Fix voltage change propagations to supply regulators

Some regulators support get_voltage and some support get_voltage_sel
operations. Do voltage change propagation only when the current
regulator has a minimum dropout voltage specified or if the current
regulator lacks both get_voltage and get_voltage_sel operations.

CRs-Fixed: 2018399
Change-Id: I24cc880d6a61c2cb489897d39a1b63199749c98d
Signed-off-by: Tirupathi Reddy <tirupath@codeaurora.org>