udev/net_id: Introduce predictable network names for Linux on System z

udev/net_id: Introduce predictable network names for Linux on System z

Use the bus-ID to create predicatable devices names for network interfaces
on Linux on System z instances.  The bus-ID identifies a device in the s390
channel subsystem.

Network interfaces of device type Ethernet are named as:
    enccw0.0.1234    (13 characters)
up to
    enccwff.7.ffff   (14 characters)

CTC network devices of device type SLIP, use a different prefix as follows:
    slccw0.0.1234    (13 characters)

See also Red Hat Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=870859
[tomegun: typical problem of netdevs switching names between reboots.]