Add debugfs support to dump the MCAM rules installed using
NPC_INSTALL_FLOW mbox message. Debugfs file can display mcam
entry, counter if any, flow type and counter hits.

Ethtool will dump the ntuple flows related to the PF only.
The debugfs file gives systemwide view of the MCAM rules
installed by all the PF's.

Below is the example output when the debugfs file is read:
~ # mount -t debugfs none /sys/kernel/debug
~ # cat /sys/kernel/debug/octeontx2/npc/mcam_rules

	Installed by: PF1
	direction: RX
        mcam entry: 227
	udp source port 23 mask 0xffff
	Forward to: PF1 VF0
        action: Direct to queue 0
	enabled: yes
        counter: 1
        hits: 0
Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>