overlayfs: add missing closing parenthesis in selftest

Cc: Vyacheslav Yurkov <uvv.mail@gmail.com>
(From OE-Core rev: aebd526cdfea738745e57183b1015fd327bd94df)

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-selftest/recipes-test/overlayfs-user/overlayfs-user.bb

@@ -18,5 +18,5 @@ do_install() {
 
 FILES:${PN} += "\
     ${exec_prefix} \
-    ${sysconfdir \
+    ${sysconfdir} \
 "