octeontx2-pf: Fix NIX1_RX interface backpressure

'bp_ena' in Aura context is NIX block index, setting it
zero will always backpressure NIX0 block, even if NIXLF
belongs to NIX1. Hence fix this by setting it appropriately
based on NIX block address.

Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>