octeontx2-af: Add NPC MCAM entry allocation status to debugfs

Added support to display current NPC MCAM entries and counter's allocation
status ín debugfs.

cat /sys/kernel/debug/octeontx2/npc/mcam_info' will dump following info
- MCAM Rx and Tx keysize
- Total MCAM entries and counters
- Current available count
- Count of number of MCAM entries and counters allocated
  by a RVU PF/VF device.

Also, one NPC MCAM counter (last one) is reserved and mapped to
NPC RX_INTF's MISS_ACTION to count dropped packets due to no MCAM
entry match. This pkt drop counter can be checked via debugfs.

Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>