net: stmmac: Introduce dwmac1000 timestamping operations

net: stmmac: Introduce dwmac1000 timestamping operations

In GMAC3_X, the timestamping configuration differs from GMAC4 in the
layout of the registers accessed to grab the number of snapshots in FIFO
as well as the register offset to grab the aux snapshot timestamp.

Introduce dedicated ops to configure timestamping on dwmac100 and
dwmac1000. The latency correction doesn't seem to exist on GMAC3, so its
corresponding operation isn't populated.

Reviewed-by: Daniel Machon <daniel.machon@microchip.com>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20241112170658.2388529-6-maxime.chevallier@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>