dt-bindings: arm: Add Keem Bay bindings

Document Intel Movidius SoC code-named Keem Bay, along with the Keem Bay
EVM board.

Link: https://lore.kernel.org/r/20200717090414.313530-3-daniele.alessandrelli@linux.intel.com


Reviewed-by: Dinh Nguyen <dinguyen@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Daniele Alessandrelli <daniele.alessandrelli@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>