feat(mt8188): enable MTK_PUBEVENT_ENABLE

Enable MTK_PUBEVENT_ENABLE for subscribing CPUPM events. This
patch also corrects the header file naming.

Change-Id: Iabd89a4ead21ccafa833390367484bfea5d351f6
diff --git a/plat/mediatek/lib/pm/mtk_pm.h b/plat/mediatek/lib/pm/mtk_pm.h
index 892a0b0..4a29439 100644
--- a/plat/mediatek/lib/pm/mtk_pm.h
+++ b/plat/mediatek/lib/pm/mtk_pm.h
@@ -9,7 +9,7 @@
 #include <lib/psci/psci.h>
 
 #if MTK_PUBEVENT_ENABLE
-#include <mtk_event/mtk_pubsub_events.h>
+#include <vendor_pubsub_events.h>
 #endif
 
 #define MTK_CPUPM_E_OK			(0)