usbnet: smsc95xx: dereferencing NULL pointer

we were dereferencing dev to initialize pdata. but just after that we
have a BUG_ON(!dev). so we were basically dereferencing the pointer
first and then tesing it for NULL.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: David S. Miller <davem@davemloft.net>