s390/qeth: remove unused code in qdio_establish_cq()

Storing the number of input buffers into 'i' has no effect, it is
immediately re-assigned in the next line.

Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Reviewed-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>