kernel-selftest: Convert to use a dedicated UNPACKDIR

Avoid following warning by using a dedicated unpack directory for sources.

WARNING: kernel-selftest-1.0-r0 do_unpack: kernel-selftest: the directory ${WORKDIR}/${BP} (/home/kraj200/yoe/build/tmp/work/qemux86_64-yoe-linux/kernel-self test/1.0/kernel-selftest-1.0) pointed to by the S variable doesn't exist - please set S within the recipe to point to where the source has been unpacked to

Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-kernel/kernel-selftest/kernel-selftest.bb

@@ -2,10 +2,13 @@ SUMMARY = "Kernel selftest for Linux"
 DESCRIPTION = "Kernel selftest for Linux"
 LICENSE = "GPL-2.0-only"
 
-LIC_FILES_CHKSUM = "file://${UNPACKDIR}/COPYING;md5=bbea815ee2795b2f4230826c0c6b8814"
+LIC_FILES_CHKSUM = "file://COPYING;md5=bbea815ee2795b2f4230826c0c6b8814"
 
 DEPENDS = "rsync-native llvm-native"
 
+S = "${WORKDIR}/sources"
+UNPACKDIR = "${S}"
+
 # for musl libc
 SRC_URI:append:libc-musl = "\
                       file://userfaultfd.patch \
@@ -108,10 +111,6 @@ do_install() {
     chown root:root  -R ${D}/usr/kernel-selftest
 }
 
-do_configure() {
-    install -D -m 0644 ${UNPACKDIR}/COPYING ${S}/COPYING
-}
-
 do_patch[prefuncs] += "copy_kselftest_source_from_kernel remove_unrelated"
 python copy_kselftest_source_from_kernel() {
     sources = (d.getVar("KERNEL_SELFTEST_SRC") or "").split()