Update API names for layerscape gen4 fixup.
Suffix layerscape_gen4 fixup API names with _ls_gen4.
This is required to organize device tree fixup in common, layerscape
and layerscape_gen4 specific code.
Signed-off-by: NWasim Khan <wasim.khan@nxp.com>
Reviewed-by: NPriyanka Jain <priyanka.jain@nxp.com>