dt-bindings: reserved-memory: Add restricted-dma-pool constraints

The "restricted-dma-pool" definition prohibits combination with either
of the "no-map" and "reusable" properties, but this is only stated in
the description text. Add those constraints to the schema so we can
properly validate them.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/a4f3d4e2feef008d1236ebc3f5f0c46360f20c60.1645119806.git.robin.murphy@arm.com