m7-common: Introduce m7vzw

Change-Id: Iff184007a7906f3fe842f0038c016974034e9217
m7-common: clean up initscripts

* m7spr has it's own set, while m7vzw shares the GSM set
* Fixes compilation for non-m7vzw variants

Change-Id: I53f877d132d8ce2c15144ff12f82232fae883c4f
Fixed rc and fstab configurations to allow device encryption

Detailed description:
   fstab entries were set up to encrypt using a footer at the end of the
partition, but the fs was not recognized by cryptfs.c as being
appropriately shortened.  Inspection of the original fstab.m7 reveals
crypt keys are stored on the "extra" block, or /dev/block/mmcblk0p27,
changed fstab to match.
   tmpfs mountpoints inside /data prevented cryptfs from unmounting /data.
Fixed this by assigning mountpoints to directories inside /mnt and
creating symbolic links to /mnt inside /data.

Change-Id: I22b390bc7e329b3f79ac3b73e02bd0c33c4b1025