The pool indices are currently hard coded throughout the code, which
makes the code hard to follow and extend.

Overcome this by using defines for the pool indices.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Reviewed-by: NPetr Machata <petrm@mellanox.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>