Disable interrupts and quiesce rx before unregistering net device to avoid crash
while unloading driver when traffic is flowing through.

Based on original work by Shameem Khalid <shameem@chelsio.com>

Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>