base-files: Fix sysupgrade overlay saving

A previous change to sysupgrade moved the overlay files into upper/
The -c switch generates a list of files to backup, but the sed
calls did not take this into consideration.

Signed-off-by: Rob Mosher <nyt-openwrt@countercultured.net>

SVN-Revision: 48281

package/base-files/files/sbin/sysupgrade

@@ -115,6 +115,7 @@ add_overlayfiles() {
 		local overlaydir="/overlay"
 	fi
 	find $overlaydir/etc/ -type f -o -type l | sed \
+		-e 's,^/overlay\/upper/,/,' \
 		-e 's,^/overlay/,/,' \
 		-e '\,/META_[a-zA-Z0-9]*$,d' \
 		-e '\,/functions.sh$,d' \