regulator: cpr-regulator: Add a DT property for min. quotient difference

There are targets where the minimum target quotient difference between the
highest and (highest - 1) fuse corner may be lower than 50. Add an optional
property to allow passing this value as platform data. If the property
is not present use a default value of 50.

CRs-Fixed: 762377
Change-Id: I72901d82743e6fb0915a7e53cefbd4861d0ca3db
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>