net: dsa: mt7530: implement .get_stats64

net: dsa: mt7530: implement .get_stats64

It was reported that the internally calculated counter might differ from
the real one from the Switch MIB. This can happen if the switch directly
forward packets between the ports or offload small packets like ARP
request. In such case, the kernel counter will desync compared to the
real one transmitted and received by the Switch.

To correctly provide the real info to the kernel, implement .get_stats64
that will directly read the current MIB counter from the switch
register.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Link: https://patch.msgid.link/20250410163022.3695-7-ansuelsmth@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>