mvpp2: remove misleading comment

Recycling in mvpp2 has gone long time ago, but two comment still refers
to it. Remove those two misleading comments as they generate confusion.

Fixes: 7ef7e1d9 ("net: mvpp2: drop useless fields in mvpp2_bm_pool and related code")
Signed-off-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>