[zircon][ulib] Move usb out of driver ulib

This changeset moves usb.c out of the driver ulib and adds a separate
library for itself. In a later changeset some of the usb-request.c
functionality will move in into this library.

Test: Build. Sanity test of usb on vim2

Change-Id: I4807a3327943a71b5b88b22ab5c49756b042d969

[dev][ethernet] Support multicast filter

Test: /system/test/sys/ethernet-test passes
Multicast filter works with AX88179:
Target-shell-1-$ netdump /dev/class/ethernet/000
(The next command may make "fx shell" fail until reboot)
Target-shell-2-$ ethtool /dev/class/ethernet/000 15 filter \
1.0.94.5.42.88
(within 15 seconds do the next command...)
Host-$ for i in `seq 0 255` ; do timeout 0.01 ping -l 1 -c 1 -Iem1 \
224.5.42.$i ; done
Target shell 1 shows receipt of 1.0.94.5.42.88 (and 3 other addresses).

NET-87 #done

Change-Id: Ideee70c3c74f186784197fc293dc555eefeb843a

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[udev][asix-88179] rename

Change-Id: I694050d388d512bd0bdb83f4e70be85ee83094ca