ibmvnic: define flush_reset_queue helper

Define and use a helper to flush the reset queue.

Fixes: 2770a798 ("ibmvnic: Introduce hard reset recovery")
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>