MPILIB: add module description and license

This patch fixes lack of license, otherwise mpi.ko taints kernel.

Signed-off-by: Konstantin Khlebnikov <[e-mail]>
Signed-off-by: David Howells <[e-mail]>

lib/mpi/mpiutil.c

···
 	kfree(a);
 }
 EXPORT_SYMBOL_GPL(mpi_free);
+
+MODULE_DESCRIPTION("Multiprecision maths library");
+MODULE_LICENSE("GPL");