dlx: update fstab

* mark boot and recovery for recoveryonly
* update deprecated prefix on usb storage

Change-Id: I3c03d3131916a6c123c1d668aa4dc387229fd75c
dlx: mount and firmware fixups

* create firmware symlinks at build time
* mount all partitions via fs_mgr

Change-Id: If50b4dce389455dc8ca668c93cb169f0afcb2707