vold: cryptfs: Retry encryption after killing processes using /data

Currently, if a non-framework process or service is using /data,
unmounting will fail as nothing will kill it.
Instead of rebooting on unmount failure, we now kill all processes
using /data, then try one more time.

Bug: 11291208
Change-Id: I6c5276c78aa55965914ace96e1db74dc80fca3c1
3 files changed