regulator: qpnp-regulator: Add support for rev 1 N1200 and N600 LDOs

The mapping between voltage control register set point values and
physical output voltage changes for range 1 of N1200 and N600
LDOs between PM8941 v1 and PM8941 v2.  LDOs with the previous
mapping have digital major revision equal to 0.  LDOs with the
new mapping have digital major revision equal to 1.  Modify the
qpnp-regulator driver so that the digital major revision register
value is taken into account when deciding which voltage mapping
to utilize.  N1200 and N600 regulators have identical
(range, voltage set point) --> output voltage mapping.

N1200 LDO range 1 hardware set points (rev=0):
375 mV to 768.75 mV with 6.25 mV step size

N1200 LDO range 1 hardware set points (rev=1):
375 mV to 1537.5 mV with 12.5 mV step size

Configure qpnp-regulator to use only range 0 for N1200 rev 1.
Range 0 is used because there is no benefit to using ranges 1 or
2 given that they have the same maximum voltage and step size
and their minimum voltage is greater than or equal to that of
range 0.

Change-Id: Icac6a1d8fccc014a754843d61c1fa40f550f9c77
Signed-off-by: David Collins <collinsd@codeaurora.org>