RegulatoryDialog : Use String.split to avoid crash on empty args

If a device only supports SAR image vs values, and empty overlay
will cause TextUtils.split to return an empty array and hence number
of format arguments will be mismatched. Instead use String.split
which returns a non-empty string array in the event that the source is empty.

Change-Id: I3d99e3378264d7b26d69ebe6c9c35c3c925f5c49
CYNGNOS-2050
(cherry picked from commit 3ac48ea9)