arm64: Add config for Keem Bay SoC

Add ARCH_KEEMBAY configuration option to support Intel Movidius SoC
code-named Keem Bay.

Link: https://lore.kernel.org/r/20200717090414.313530-2-daniele.alessandrelli@linux.intel.com


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