platform/surface: Replace deprecated strcpy() in surface_button_add()

platform/surface: Replace deprecated strcpy() in surface_button_add()

strcpy() has been deprecated [1] because it performs no bounds checking
on the destination buffer, which can lead to buffer overflows. Replace
it with the safer strscpy().  No functional changes.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://patch.msgid.link/20260105145045.52764-2-thorsten.blum@linux.dev
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>