net: usb: ax88179_178a: non necessary second random mac address

If the mac address can not be read from the device registers or the
devicetree, a random address is generated, but this was already done from
usbnet_probe, so it is not necessary to call eth_hw_addr_random from here
again to generate another random address.

Indeed, when reset was also executed from bind, generate another random mac
address invalidated the check from usbnet_probe to configure if the assigned
mac address for the interface was random or not, because it is comparing
with the initial generated random address. Now, with only a reset from open
operation, it is just a harmless simplification.

Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>