net: qed: Remove unnecessary cast

In qed_rdma_destroy_cq() the result of dma_alloc_coherent() is cast from
void* unnecessarily. Remove cast.

Issue identified with Coccinelle.

Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>