open misc device in write-only mode

Opening the misc block device in read-write mode runs afoul of
SELinux, which keeps the wipe code from working.  Fix.  Also change
various things to log to logcat so we can see them happening, for
future debugging.

Bug: 16715412
Change-Id: Ia14066f0a371cd605fcb544547b58a41acca70b9
2 files changed