Updates for kirkstone

Changes:
- Updated LAYERSERIES_COMPAT.
- Updated override syntax via a combination of the conversion script
  in poky and manual inspection.
- Updated a license field viarunning the conversion script in poky.
- Updated branches in README, further updates will likely be required
  when an official Renesas BSP release is made.

Bug-AGL: SPEC-3819

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I6f736f56a23ddb634232e5c99e21830bc6637764