Fix initialize the uninitialized tx_qlen to an appropriate value when USB
Full Speed is used.
Fixes: 55d7de9de6c3 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver") Signed-off-by: Yuiko Oshino <yuiko.oshino@microchip.com> Signed-off-by: David S. Miller <davem@davemloft.net>