Add mbuf defragmentation to the ENA driver
When mbuf chain is too long and device cannot handle that number
of segments in DMA transaction, mbuf chain will be defragmented.
Initially, driver was dropping all mbuf chains that were exceeding
supported number of segments.
Submitted by: Michal Krawczyk <firstname.lastname@example.org>
Obtained from: Semihalf
Sponsored by: Amazon.com Inc.
Differential revision: https://reviews.freebsd.org/D10923