trees: remove unnecessary command

we no longer need to remove cache/ per project, because
it's removed in bulk at the end, in the main build script,
when generating release archives.

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

script/trees

@@ -37,8 +37,7 @@ main()
 	done
 	[ -z "$_f" ] && $err "missing flag (-m/-u/-b/-c/-x/-f/-s/-l/-n)"
 	[ -z "$project" ] && for p in $(ls -1 config/git); do
-		./update trees $_f "$p" || $err "!./update trees $_f $p"
-		[ "$XBMK_RELEASE" != "y" ] || x_ rm -Rf "cache/repo/$p"; :
+		./update trees $_f "$p" || $err "!./update trees $_f $p"; :
 	done && return 1
 
 	[ -f "config/git/$project/pkg.cfg" ] || $err "'$project' not defined"