net: vmxnet3: remove unnecessary pci_set_drvdata()

The driver core clears the driver data to NULL after device_release
or on probe failure. Thus, it is not needed to manually clear the
device driver data to NULL.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Shreyas N Bhatewara <sbhatewara@vmware.com>
Acked-by: Dmitry Torokhov <dtor@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>