ofnet: Do not set SUFFIX for sun4v network devices

ofnet: Do not set SUFFIX for sun4v network devices

sun4v vnet devices do not implement the support of duplex and speed
instance attributes. An attempt to open such a device with
the attributes will fail:

ok select net:speed=auto,duplex=auto
Unknown key 'speed'
Unknown key 'duplex'
Manual Configuration: Host IP, boot server and filename must be specified
WARNING: /virtual-devices@100/channel-devices@200/network@0: Can't open OBP standard TFTP package

Can't open device
ok

Therefore, let's not set SUFFIX for such devices.

Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>