fix typo

Signed-off-by: Carl Schwan <carl@carlschwan.eu>

lib/private/Memcache/ProfilerWrapperCache.php

@@ -54,7 +54,7 @@ public function get($key) {
 	/** @inheritDoc */
 	public function set($key, $value, $ttl = 0) {
 		$start = microtime(true);
-		$ret = $this->wrappedCache->set($key, $value, $$ttl);
+		$ret = $this->wrappedCache->set($key, $value, $ttl);
 		$this->data['queries'][] = [
 			'start' => $start,
 			'end' => microtime(true),