ibmvnic: Do not process device remove during device reset

The ibmvnic driver does not check the device state when the device
is removed. If the device is removed while a device reset is being
processed, the remove may free structures needed by the reset,
causing an oops.

Fix this by checking the device state before processing device remove.

Signed-off-by: Juliet Kim <julietk@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>