net: lantiq_etop: replace strlcpy with strscpy

strlcpy is marked as deprecated in Documentation/process/deprecated.rst,
and there is no functional difference when the caller expects truncation
(when not checking the return value). strscpy is relatively better as it
also avoids scanning the whole source string.

This silences the related checkpatch warnings from:
commit 5dbdb2d8 ("checkpatch: prefer strscpy to strlcpy")

Signed-off-by: Aleksander Jan Bajkowski <olek2@wp.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>