cryptfs: also unmount /data/data before encrypting

galaxysmtd mounts /data/data on top on /data when unencrypted for
performance reason, so when encrypting, we need to unmount that
first before we can unmount /data.

On other devices, umount on a non-mounted folder will silently
succeed.

Signed-off-by: Humberto Borba <humberos@gmail.com>
Change-Id: I07a73534fb3e253b702a4be6f976594644795e36
Merge "cryptfs: also unmount /data/data before encrypting" into android-4.4
[2/3] Vold: NTFS support

omni: https://gerrit.omnirom.org/#/c/5170/
android: https://gerrit.omnirom.org/#/c/5172/

Change-Id: I6757d78c98837e02975c37ca20d6e6b9e36ced69
Merge branch 'android-4.4' of https://github.com/omnirom/android_system_vold into HEAD

Conflicts:
	Volume.cpp