net: phy: mscc: Fix memory leak when using one step timestamping

Fix memory leak when running one-step timestamping. When running
one-step sync timestamping, the HW is configured to insert the TX time
into the frame, so there is no reason to keep the skb anymore. As in
this case the HW will never generate an interrupt to say that the frame
was timestamped, then the frame will never released.
Fix this by freeing the frame in case of one-step timestamping.

Fixes: 7d272e63 ("net: phy: mscc: timestamping and PHC support")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Link: https://patch.msgid.link/20250522115722.2827199-1-horatiu.vultur@microchip.com


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