net/enic: fix crash on MTU update or Rx queue reconfigure

net/enic: fix crash on MTU update or Rx queue reconfigure

The incorrect completion queue corresponding to an RQ would be
freed if multiple Rx queues are in use and the MTU is changed,
or an Rx queue is released. This could lead to a segmentation fault
when the device is disabled or even in the Rx or Tx paths.

The index of the completion queue corresponding to a RQ needed
to be adjusted after Rx scatter was introduced.

Fixes: 856d7ba7ed22 ("net/enic: support scattered Rx")

Signed-off-by: John Daley <johndale@cisco.com>
Reviewed-by: Nelson Escobar <neescoba@cisco.com>