octeontx2-af: Fix mapping for NIX block from CGX connection

Firmware configures NIX block mapping for all MAC blocks.
The current implementation reads the configuration and
creates the mapping between RVU PF  and NIX blocks. But
this configuration is only valid for silicons that support
multiple blocks. For all other silicons, all MAC blocks
map to NIX0.

This patch corrects the mapping by adding a check for the same.

Fixes: c5a73b63

 ("octeontx2-af: Map NIX block from CGX connection")
Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>