ewaol-config,doc: Depend on the kirkstone branch of meta-virtualization

The kirkstone branch of meta-virtualization has been created, so this patch
tracks it instead of master.

As meta-virtualization kirkstone has bumped Xen to version 4.16, also update the
documentation.

Issue-Id: SCM-4394
Signed-off-by: Richard Neill <richard.neill@arm.com>
Change-Id: I0fcd9a3d9614e7949e8681df79288127d308fa61