m68k: setup: Remove size argument when calling strscpy()

The size parameter of strscpy() is optional and specifying the size of
the destination buffer is unnecessary. Remove it to simplify the code.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Tested-by: Jean-Michel Hautbois <jeanmichel.hautbois@yoseli.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/20250302230532.245884-2-thorsten.blum@linux.dev


Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>