octeontx2-af: Debugfs support for DMAC filters

Add debugfs support to display CGX/RPM DMAC filter
table associated with pf.

cat /sys/kernel/debug/octeontx2/cgx/cgx0/lmac0/mac_filter

PCI dev       RVUPF  BROADCAST  MULTICAST  FILTER-MODE
0002:02:00.0  PF2    ACCEPT     ACCEPT     UNICAST

DMAC-INDEX  ADDRESS
      0     00:0f:b7:06:17:06
      1     1a:1b:1c:1d:1e:01
      2     1a:1b:1c:1d:1e:02

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