Update for kirkstone variable renames

Update for kirkstone variable renames

Apply updates from running the new convert-variable-renames script
from upstream, plus a few manual tweaks to the sample BB_DISKMON_DIRS
configuration in the sample local.conf files to match the changes
made in upstream.  There are a few things outside of BitBake variables
that the script still complains about that will need to be addressed
in follow up changes.

Bug-AGL: SPEC-3819

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I65e483043c1f2e48827e735cf8fdaec8d04e5fee