Add support for reporting PHY statistics in the DP83TD510 driver. This
includes cumulative tracking of transmit/receive packet counts, and
error counts. Implemented functions to update and provide statistics via
ethtool, with optional polling support enabled through `PHY_POLL_STATS`.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> Signed-off-by: Paolo Abeni <pabeni@redhat.com>