hyperv: Remove useless channel inbound_lock

It serves no purpose.

Reviewed by:        Hongjiang Zhang <honzhan microsoft com>
MFC after:  1 week
Sponsored by:       Microsoft OSTC
Differential Revision:      https://reviews.freebsd.org/D5450

hyperv: Always set device for channels

And unregister hv_device only for primary channels, who own the hv_device.

MFC after:  1 week
Sponsored by:       Microsoft OSTC
Differential Revision:      https://reviews.freebsd.org/D5451

hyperv/hn: Pass channel as the channel callback argument

This is the preamble to pass channel back to hn(4) upon TX/RX done.

Reviewed by:        Hongjiang Zhang <honzhan microsoft com>
MFC after:  1 week
Sponsored by:       Microsoft OSTC
Differential Revision:      https://reviews.freebsd.org/D5452

hyperv/hn: Pass channel to TX/RX done

This is preamble to associate the TX/RX rings to their channel.

While I'm here, revoke unused netvsc_recv_rollup.

MFC after:  1 week
Sponsored by:       Microsoft OSTC
Differential Revision:      https://reviews.freebsd.org/D5453

hyperv/hn: Associate TX/RX ring with channel

This fixes the TX/RX ring selection for TX/RX done.

MFC after:  1 week
Sponsored by:       Microsoft OSTC
Differential Revision:      https://reviews.freebsd.org/D5454

hyperv/hn: Remove the useless num_outstanding_sends

We rely on taskqueue draining now.

MFC after:  1 week
Sponsored by:       Microsoft OSTC
Differential Revision:      https://reviews.freebsd.org/D5456

hyperv/hn: Make transmission path channel aware

Chimney sending buffer still needs conversion, which will be done
along with the upcoming vRSS support.

MFC after:  1 week
Sponsored by:       Microsoft OSTC
Differential Revision:      https://reviews.freebsd.org/D5457