Remove pointless U-Boot PREFERRED_VERSION, as meta-sunxi no longer
provides its own u-boot recipe.
Signed-off-by: Diego Rondini <diego.rondini@kynetics.com>
Update stable to 4.13.4 version thus removing backported patch and requirement
of git version for several boards (current stable 4.13 is newer than previous
git 4.11).
Additionally update git version to 4.14-rc3.
Signed-off-by: Diego Rondini <diego.rondini@kynetics.com>