Change priv-apps /home/home labels to privapp_data_file

Currently, both untrusted apps and priv-apps use the SELinux file label
"app_data_file" for files in their /data/data directory. This is
problematic, as we really want different rules for such files. For
example, we may want to allow untrusted apps to load executable code
from priv-app directories, but disallow untrusted apps from loading
executable code from their own home directories.

Commit 23c9d91b introduced a new type
called privapp_data_file and added rules necessary to preserve
compatibility. However, that change did not relabel any existing files,
so effectively the change was a no-op.

This change performs the switch, relabeling priv-app's /data/data files
from app_data_file to privapp_data_file. Due to the compatibility rules
added in 23c9d91b, there should be no
noticeable effect from this change.

Test: Factory reset and boot - no problems on fresh install.
Test: Upgrade to new version and test. No compatibility problems on
      filesystem upgrade.

Merged-In: I9a476726bf01f4bcc7952d11fd57dba803a9fd8d
Change-Id: I23a26cd3906fc43cbd225c05c3a2abd3cab8bd06