regulator: cp9314: Adds support for HW I2C Lock feature

Adds support for the control port write-lock feature introduced in
revision B1. The write-lock feature minimizes the risk of spurious
I2C writes flipping sensitive bits during device operation by blocking
writes to some or all of the register map.

If desired, the write-lock must be set in hardware by biasing PGPIO2
appropriately and setting the cirrus,hw-i2c-lock flag in the devicetree
entry.

Signed-off-by: Ricardo Rivera-Matos <rriveram@opensource.cirrus.com>