ibmvnic: skip send_request_unmap for timeout reset

Timeout reset will trigger the VIOS to unmap it automatically,
similarly as FAILVOER and MOBILITY events. If we unmap it
in the linux side, we will see errors like
"30000003: Error 4 in REQUEST_UNMAP_RSP".
So, don't call send_request_unmap for timeout reset.

Fixes: ed651a10

 ("ibmvnic: Updated reset handling")
Signed-off-by: Lijun Pan <ljp@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>