This variable is needed by testextsdk to known the name of extensible
sdk file generated.
(From OE-Core rev: e4cf46f240dda6263ba3ba14cd63087cce166f1c)
Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>