linux-imx-[mfgtool]-5.4.3: update recipes to align with kernel-yocto
When kernel-yocto class is inherited by kernel recipes, the way how PV
is constructed changes to reflect GIT kernel tags and meta information.
This causes the fetcher search to fail, since paths used to locate files
are compiled from PV.
Replace version-specific paths in recipes to use PN instead, which is
registered in the fetcher as a valid search location.
Linux kernel recipe should have LINUX_VERSION also defined, since it is
used by kernel-yocto class to derive PV. This version is set to the real
kernel version provided by NXP in their source tree.
