ARM: dts: msm: modify LAB/IBB required configuration for PMI8950

As per the hardware documentation, modify the following
configurations, LAB max precharge time, IBB power-up and
power-down delay needed for targets using PMI8950.

Change-Id: I810bce5daf6151563b49a36acbed39c8035fd1af
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>