dt-bindings: remove 'interrupt-parent' from bindings

'interrupt-parent' is often documented as part of define bindings, but
it is really outside the scope of a device binding. It's never required
in a given node as it is often inherited from a parent node. Or it can
be implicit if a parent node is an 'interrupt-controller' node. So
remove it from all the binding files.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

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>

dt: Move device tree documentation out of powerpc directory

The device tree is used by more than just PowerPC. Make the documentation
directory available to all.

v2: reorganized files while moving to create arch and driver specific
directories.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>