xfs_protofile: rename source code to .py.in

xfs_protofile: rename source code to .py.in

Rename this source code file to have an extention of ".py.in" so that
editors and xgettext can "smartly" detect the source code type from the
file extension.  This will become important for adding localization to
the strings printed.  No functional changes.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Andrey Albershteyn <aalbersh@kernel.org>
Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>