powerpc/fsl: Add/update miscellaneous missing binding

Missing bindings were found on running checkpatch.pl on bsc9132
device tree. This patch add/update the following

- Add bindings for L2 cache controller
- Add bindings for memory controller
- Update bindings for USB controller

Signed-off-by: Harninder Rai <harninder.rai@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>