net: dsa: lantiq_gswip: add terminating \n where missing

Some dev_err are missing the terminating \n. Let's add that.

Suggested-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Martin Schiller <ms@dev.tdt.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20240611135434.3180973-4-ms@dev.tdt.de


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