Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC: r243857 (partial)

Mechanically substitute flags from historic mbuf allocator with
malloc(9) flags in sys/dev.

MFC r232946,232958,235233:

r232946:
Update the rt2860's firmware and add a Makefile for the module. While
here remove the ucode header file which was used to generate the fw files
but by now is outdated.

r232958:
Import the latest microcode.h which was used to generate the current
firmware files and adjust the Makefile.

r235233:
Add support for Ralink RT2800/RT3000 chipsets.

Add support for Ralink RT2800/RT3000 chipsets.

Thanks to ray@, Sevan and Sergey Dyatko for feedback and testing!

Obtained from: OpenBSD
MFC after: 3 weeks