Hello,
As Shivani says, you need to see if you are using the wayland distro. Otherwise, you cannot start the weston process. Another way to make that is with the below command line when you are initializing the building machine.
DISTTO=fsl-imx-wayland MACHINE=<your machine name> source fsl-setup-release.sh -b <your build dir>
Whit that initialization, you should see the local.conf file with the configuration that Shivani says.
Hope this can help you.
Best regards,
Diego.