As commit 7ae4a78d ("ARM: 8969/1: decompressor: simplify libfdt
builds") stated, copying source files during the build time may not
end up with as clean code as expected.

Do similar for parisc to clean up the Makefile.
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
Acked-by: NHelge Deller <deller@gmx.de>
Signed-off-by: NHelge Deller <deller@gmx.de>