regulator: cpr-regulator: add support for target quotient fuse size

The CPR target quotient register fields have a length of 12 bits.
However, some targets have a very limited number of fuse bits and
thus encode the target quotients for the different voltage
corners with less than 12 bits.  Add support in the cpr-regulator
driver for the optional device tree property
qcom,cpr-fuse-target-quot-size which can be used to specify the
bit length of the target quotient fuse values for each corner.

Change-Id: Ibdb3e2b1adc415480fdf47977b9d1b8c3dc0193d
Signed-off-by: David Collins <collinsd@codeaurora.org>