phy: add hwtstamp_get callback to phy drivers

phy: add hwtstamp_get callback to phy drivers

PHY devices had lack of hwtstamp_get callback even though most of them
are tracking configuration info. Introduce new call back to
mii_timestamper.

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Signed-off-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://patch.msgid.link/20251124181151.277256-3-vadim.fedorenko@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>