machine: imx[6,7,8]: update dtb references for 5.4 kernel
Updated kernel has some DTS files added and some dropped for various
i.MX derivatives. Those should be aligned with respective machines in
order to deliver proper DTB files, and do not fail the build for those
are missing.
Device tree files listed in respective machines are those only present
in updated 5.4 kernel release from NXP. Derivatives, which relied on
those device trees that are discarded from the new kernel release should
backport their respective files onto that update.
In other words: if after this update the DTS file used for the HW happens
to be missing - it should be manually added for that HW, since the default
version is no longer provided by NXP in their updated kernel tree.
