feat(plat/imx/imx8m/imx8mp): add imx8mp_private.h to the build

Allows for exporting of FIP related methods cleanly in a private header.

Signed-off-by: Ying-Chun Liu (PaulLiu) <paulliu@debian.org>
Change-Id: Iaaad4e69ef89c8a8a74648647d7fd09cd0fdd12a
diff --git a/plat/imx/imx8m/imx8mp/include/imx8mp_private.h b/plat/imx/imx8m/imx8mp/include/imx8mp_private.h
new file mode 100644
index 0000000..0a02334
--- /dev/null
+++ b/plat/imx/imx8m/imx8mp/include/imx8mp_private.h
@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2021, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef IMX8MP_PRIVATE_H
+#define IMX8MP_PRIVATE_H
+
+/*******************************************************************************
+ * Function and variable prototypes
+ ******************************************************************************/
+void plat_imx_io_setup(void);
+
+#endif /* IMX8MP_PRIVATE_H */