apalis-imx8qm: rename all occurences to apalis-imx8

The Toradex product is called apalis-imx8 consisting of SoM with
i.MX8QM and i.MX8QP SoCs.

Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Reviewed-by: Igor Opaniuk <igor.opaniuk@toradex.com>