net: enetc: add debugfs interface to dump MAC filter

net: enetc: add debugfs interface to dump MAC filter

ENETC's MAC filter consists of hash MAC filter and exact MAC filter.
Hash MAC filter is a 64-bit entry hash table consisting of two 32-bit
registers. Exact MAC filter is implemented by configuring MAC address
filter table through command BD ring. The table is stored in ENETC's
internal memory and needs to be read through command BD ring. In order
to facilitate debugging, added a debugfs interface to get the relevant
information about MAC filter.

Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20250506080735.3444381-6-wei.fang@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>