octeontx2-af: cn10K: Get NPC counters value

The way SW can identify the number NPC counters supported by silicon
has changed for CN10K. This patch addresses this reading appropriate
registers to find out number of counters available.

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