net: lan969x: fix the use of spin_lock in PTP handler

We are mixing the use of spin_lock() and spin_lock_irqsave() functions
in the PTP handler of lan969x. Fix this by correctly using the _irqsave
variants.

Fixes: 24fe8354 ("net: lan969x: add PTP handler function")
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>

[1]: https://lore.kernel.org/netdev/20241024-sparx5-lan969x-switch-driver-2-v2-10-a0b5fae88a0f@microchip.com/



Signed-off-by: David S. Miller <davem@davemloft.net>