m7vzw: update system props (again)

telephony.rilV7NeedCDMALTEPhone is deprecated.

I was overzealous in removing some props that are used by proprietary
libs (run strings on the ril libs). These are being re-included:
persist.radio.add_power_save
persist.radio.snapshot_enabled
persist.radio.snapshot_timer
ro.ril.wp.feature

Change-Id: I9ba02340c26b8c6dcc90574a58326d3d17223474