[3] is build-time generated by scripts/Makefile.asm-generic.
However, -I$(srctree)/arch/$(hdr-arch)/include search path is listed
before -I$(objtree)/arch/$(hdr-arch)/include/generated in LINUXINCLUDE.
Therefore [1] is always included instead of [3]. Remove [3] which
is never included.
If we look at [1], it just includes [2]. So, [1] can be removed
as well.