feat(mt8196): add SMMU SID stub implementation

Add stub implementation for SMMU SID driver.

Change-Id: Ia29fd72fb40e7ce372a27a748e0caac3300f045f
Signed-off-by: Yidi Lin <yidilin@chromium.org>
diff --git a/plat/mediatek/include/mtk_bl31_interface.h b/plat/mediatek/include/mtk_bl31_interface.h
index a74fa17..208276c 100644
--- a/plat/mediatek/include/mtk_bl31_interface.h
+++ b/plat/mediatek/include/mtk_bl31_interface.h
@@ -85,4 +85,7 @@
 void cpu_qos_change_dcc(uint32_t on, uint32_t is_auto);
 void *cpu_qos_handle_cluster_on_event(const void *arg);
 
+/* SMMU sid interfaces */
+int smmu_sid_init(void);
+
 #endif /* __MTK_BL31_INTERFACE_H__ */