qed: Delete redundant check on dcb_app priority

dcb_app priority is unsigned thus checking whether it is less than zero
is redundant.

Signed-off-by: Christos Gkekas <chris.gekas@gmail.com>
Acked-By: Tomer Tayar <Tomer.Tayar@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>