net: cadence: macb: Report standard stats

Report standard statistics using the dedicated callbacks instead of
get_ethtool_stats.

OCTTX is split over two registers. Accumulating these registers
separately in gem_stats just means we need to combine them again later.
Instead, combine these stats before saving them, like is done for
ethtool_stats.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Link: https://patch.msgid.link/20250214212703.2618652-3-sean.anderson@linux.dev


Signed-off-by: Jakub Kicinski <kuba@kernel.org>