board: msm7x27a: Correct the operating voltage range.

As per the PMIC team right operating voltage range is 3.2 to 4.2V.
So correcting the voltage range to this. The Android framework pops
up low battery warning at 14% of the remaining baterry capacity.
With this new range 14% would be at 3.34V. So fill this voltage in
fail_safe_voltage in the board file so that target wakes up incase
it reaches this voltage when its asleep.

Change-Id: Iaac840578927bd14b685ddb841e2cd20d3772197
CRs-Fixed: 366506
Signed-off-by: Krishna Vanka <kvanka@codeaurora.org>