Removed traces of the deprecated KBRANCH_DEFAULT variable.
(From yocto-docs rev: 8130f0db46be872cd857d8579323e4ad00da6380)
Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>