map_storep was not being vfree()'d in the module_exit call.

Cc: <stable@vger.kernel.org>
Signed-off-by: NEwan D. Milne <emilne@redhat.com>
Reviewed-by: NLaurence Oberman <loberman@redhat.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>