fixed mistake in nsec computation
fixed mistake in nsec computation

ntop/PF_RING,ntop/PF_RING,ntop/PF_RING,ntop/PF_RING,ntop/PF_RING,ntop/PF_RING,opencTM/PF_RING,opencTM/PF_RING,opencTM/PF_RING,ntop/PF_RING,opencTM/PF_RING