net: mscc: ocelot: fix memory leak on ocelot_port_add_txtstamp_skb()

net: mscc: ocelot: fix memory leak on ocelot_port_add_txtstamp_skb()

If ocelot_port_add_txtstamp_skb() fails, for example due to a full PTP
timestamp FIFO, we must undo the skb_clone_sk() call with kfree_skb().
Otherwise, the reference to the skb clone is lost.

Fixes: 52849bcf0029 ("net: mscc: ocelot: avoid overflowing the PTP timestamp FIFO")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241205145519.1236778-2-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>