msm: cpr: Add software margin to the error steps

As per chip characterization recommendation, add a step
to up error steps to increase system stability and deduct
2 steps from down error steps to decrease chances of getting
closer to the system level Vmin, thereby improving stability

Change-Id: I3fb00183cd91192c53a6fbbd98932f4ea58cbf39
Signed-off-by: Kaushal Kumar <kaushalk@codeaurora.org>