[CORE] net: Gradually increasing timeouts for netswitch_bh_ring_dequeue()

Currently, we use fixed timeout for netswitch_bh_ring_dequeue() which
is very harsh on stream of packets which come at non-uniform rate.

In real world, packets always come at non-uniform rate hence the
timeout used in netswitch_bh_ring_dequeue() should start with minimum
and gradually increase so that if we have momemtary delays in stream
of packets then we don't accidently sleep for long time.

Signed-off-by: Anup Patel <anup@brainfault.org>