Convert vmx(4) to being an iflib driver.
Also, expose IFLIB_MAX_RX_SEGS to iflib drivers and add
iflib_dma_alloc_align() to the iflib API.
Performance is generally better with the tunable/sysctl
Reviewed by: shurd
Sponsored by: RG Nets
Differential Revision: https://reviews.freebsd.org/D18761
Add missing dependency to vmxnet3 Makefile and clean it up a bit otherwise.
Fix interrupt index configuration when using MSI interrupts.
When in MSI mode, the device was only being configured with one
interrupt index, but it needs two - one for the actual interrupt and
one to park the tx queue at.
Also clarified comments relating to interrupt index assignment.
Reported by: Yuri Pankov <firstname.lastname@example.org>