Fix module tainting message:

  sigma: module license 'unspecified' taints kernel.
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Acked-by: NMike Frysinger <vapier@gentoo.org>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>