scripts: get_abi.pl: make undefined search more deterministic

Sort keys on hashes during undefined search, in order to
make the script more deterministic.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/5dc55fd42e632a24a48f95212aa6c6bc4b2d11fd.1632865873.git.mchehab+huawei@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>