In Yocto 1.7 meta-fsl-arm replaced udev-extraconf bbappend with a new
package (udev-rules-imx). So we need to adapt our own bbappend to these
changes so all the needed udev rules are in place.
https://jira.digi.com/browse/DEL-1336
Signed-off-by: Javier Viguera <javier.viguera@digi.com>