feat(plat/mediatek/mt8186): add pwrap and pmic driver

1. Add 8186 pwrap driver to access pmic.
2. Add 6366 pmic driver to support clean PWRHOLD.

TEST=build pass
BUG=b:202871018

Signed-off-by: James Lo <james.lo@mediatek.corp-partner.google.com>
Change-Id: I3bc90460a6a55dff8d3293e04482abcad789bbb2
diff --git a/plat/mediatek/mt8186/drivers/pmic/pmic.h b/plat/mediatek/mt8186/drivers/pmic/pmic.h
new file mode 100644
index 0000000..91ccb19
--- /dev/null
+++ b/plat/mediatek/mt8186/drivers/pmic/pmic.h
@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2021, MediaTek Inc. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef PMIC_H
+#define PMIC_H
+
+#include <stdint.h>
+
+#define PMIC_RG_HWCID_ADDR 0x8
+#define PMIC_PWRHOLD 0xa08
+
+/* external API */
+uint32_t pmic_get_hwcid(void);
+void pmic_power_off(void);
+
+#endif /* PMIC_H */