Use /libdata/firmware/run instead of /libdata/firmware/rum for run(4) firmwares.

Add a driver for Ralink Technology RT2700U/RT2800U/RT3000U USB IEEE
802.11a/b/g/n wireless network devices, ported from OpenBSD by FUKAUMI Naoki,
arranged by me.

Add rum(4) for newer USB Ralink devices. Obtained from OpenBSD.
Special thanks to Sepherosa Ziehau for helping debugging USB issues.
Hook up rum(4) for i386 config files.