ibmvnic: Clean up device close

Remove some dead code now that RX pools are being cleaned. This
was included to wait until any pending RX queue interrupts are
processed, but NAPI polling should be disabled by this point.

Another minor change is to use the net device parameter for any
print functions instead of accessing it from the adapter structure.

Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>