regulator: qpnp-labibb: add secure writing functions for LAB/IBB registers

Currently, there is some redundant code to write securely to the
LAB/IBB module registers. Add functions qpnp_labibb_sec_write()
and qpnp_labibb_sec_masked_write() to write to the registers that
needs secure access.

While at it, add a pr_fmt() for LABIBB regulator driver to have
the messages printed out in a nice way.

Change-Id: Id42b60aba6d4611e3ea30480e16469952083c43b
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>