API doc comments in QEMU are supposed to be in kerneldoc format, so
drop Doxygen format used on v9fs_co_run_in_worker() macro.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <a8fdf0290d1e40a68f5577f29aeae12298b70733.1646314856.git.qemu_oss@crudebyte.com>