platform/x86: serial-multi-instantiate: Use 2-argument strscpy()

platform/x86: serial-multi-instantiate: Use 2-argument strscpy()

Use 2-argument strscpy(), which is not only shorter but also provides
an additional check that destination buffer is an array.

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20240602090244.1666360-5-andy.shevchenko@gmail.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>