db845c: Enable metadata encryption

This fully enables metadata encryption on db845c by following
the instructions here:
  https://source.android.com/security/encryption/metadata?hl=en

Mostly just adding --early/--late mountall arguments in the
init.rc and the "latemount" and
"keydirectory=/metadata/vold/metadata_encryption" options to the
userdata fstab line.

Note: You will likely need to flash new userdata (and possibly
reflash metadata as well) after applying this. Use the flashall
script if you are having any trouble.

Reported-by: Lucas Henneman <henneman@google.com>
Test: atest vts_kernel_encryption_test
Signed-off-by: John Stultz <john.stultz@linaro.org>
Change-Id: I3f4237267238dbf43a9c540f815ce2f00f8ae793
2 files changed