recipes: Switch away from S = WORKDIR

Where recipes use S = ${WORKDIR}, change them to set UNPACKDIR to
a subdir of WORKDIR and make S point at this instead.

I've chosen not to force S into any standard UNPACKDIR we may pick in
future just so the S = UNPACKDIR case is clearly visible by the
directory naming under WORKDIR as that should aid usability.

(From OE-Core rev: d9328e3b0b062f0621de3d114584b44f384a1c02)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-kernel/kmod/depmodwrapper-cross_1.0.bb

@@ -1,7 +1,8 @@
 SUMMARY = "Wrapper script for the Linux kernel module dependency indexer"
 LICENSE = "MIT"
 
-S = "${WORKDIR}"
+S = "${WORKDIR}/sources"
+UNPACKDIR = "${S}"
 
 INHIBIT_DEFAULT_DEPS = "1"
 # The kernel and the staging dir for it is machine specific