meta-poky: set S from UNPACKDIR in recipes that use only local files

There is no need to have two assignments; also setting S from
UNPACKDIR (and not vice versa) is more logical as unpack
task comes first, and tasks that come after unpack use S to access
unpack results.

(From meta-yocto rev: 9fb052b0f19bdd4e1b1625865c41ab8a35d7b669)

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-poky/recipes-core/tiny-init/tiny-init.bb

@@ -11,8 +11,7 @@ SRC_URI = "file://init \
 	   file://rc.local.sample \
 	  "
 
-S = "${WORKDIR}/sources"
-UNPACKDIR = "${S}"
+S = "${UNPACKDIR}"
 
 do_configure() {
 	: