realtekwifi/rtwn: Synchronize with FreeBSD trunk as of today.

A few changes ommitted (e.g. NET_EPOCH) as they are not needed.
Adds support for a variety of USB devices and one PCI device.

realtekwifi: Sync with FreeBSD trunk.

This includes changes to support the 8188EE device, as well as a
number of critical bugfixes to 8192EE devices, which should make
the driver much more stable and reliable overall.