trees: remove repo/p, not src/p/p

repo/p/ does not have its revision reset, so it
changes unpredictably, and it's not used in builds.

this used to be src/p/p/ - the context here is multi-tree
projects, in source archives.

Signed-off-by: Leah Rowe <leah@libreboot.org>

script/trees

@@ -39,7 +39,7 @@ main()
 	[ -z "$project" ] && for p in $(ls -1 config/git); do
 		./update trees $_f "$p" || $err "!./update trees $_f $p"
 		[ "$XBMK_RELEASE" != "y" ] || singletree "$p" || \
-		    x_ rm -Rf "src/$p/$p"; continue
+		    x_ rm -Rf "repo/$p"; continue
 	done && return 1
 
 	[ -f "config/git/$project/pkg.cfg" ] || $err "'$project' not defined"