Passing None to split_versions() will raise an exception, so check that
the version is specified before passing it in.
(From OE-Core rev: a530aee6d9b2b63ab5fa780b1761eac759e8c833)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>