ewaol-config,doc: Add dependency on meta-arm for EWAOL SDK images

EWAOL SDK distribution images require meta-arm and meta-arm-toolchain layer, as
the gator-daemon package is installed on the rootfs.

Issue-Id: SCM-4394
Signed-off-by: Diego Sueiro <diego.sueiro@arm.com>
Change-Id: If67534b5b2497c522c9ab06f58205ca3a0783464