Add initial device tree for Keem Bay EVM board. With this minimal device
tree the board boots fine using an initramfs image.

Link: https://lore.kernel.org/r/20200717090414.313530-6-daniele.alessandrelli@linux.intel.comReviewed-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Daniele Alessandrelli <daniele.alessandrelli@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>