regulator: qpnp-labibb-regulator: fix the base address usage

There is a bug in qpnp_lab_dt_init where the wrong base address is
used (ibb_base instead of lab_base). This causes a probe failure
in the driver because ibb_base is not available yet. Fix it.

Change-Id: I66e4c50a82f076e5582b5df0dbd18ead392dcff3
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>