usbnet: smsc95xx: fix rx packet alignment

The smsc95xx driver already takes into account the NET_IP_ALIGN
parameter when setting up the receive packet data, which means
we do not need to worry about aligning the packets in the usbnet
driver.

Adding the EVENT_NO_IP_ALIGN means that the IPv4 header is now
passed to the ip_rcv() routine with the start on an aligned address.

Tested on Raspberry Pi B3.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>