octeontx2-af: Add debugfs support to dump NIX TM topology

This patch adds support to dump NIX transmit queue topology.
There are multiple levels of scheduling/shaping supported by
NIX and a packet traverses through multiple levels before sending
the packet out. At each level, there are set of scheduling/shaping
rules applied to a packet flow.

Each packet traverses through multiple levels
SQ->SMQ->TL4->TL3->TL2->TL1 and these levels are mapped in a parent-child
relationship.

This patch dumps the debug information related to all TM Levels in
the following way.

Example:
$ echo <nixlf> > /sys/kernel/debug/octeontx2/nix/tm_tree
$ cat /sys/kernel/debug/octeontx2/nix/tm_tree

A more desriptive set of registers at each level can be dumped
in the following way.

Example:
$ echo <nixlf> > /sys/kernel/debug/octeontx2/nix/tm_topo
$ cat /sys/kernel/debug/octeontx2/nix/tm_topo

Signed-off-by: Anshumali Gaur <agaur@marvell.com>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>