board: apalis-imx8: add reset code

With commit 922d4504 ("imx: scu_api: update to version 1.16 and
add more APIs") added the reboot API.

Add the board code to use that.

Signed-off-by: Andrejs Cainikovs <andrejs.cainikovs@toradex.com>
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>