stm32mp: add check of cpu identifier

Add support of DBGMCU_IDC for cpu identifier
and revision

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>

arch/arm/mach-stm32mp/include/mach/sys_proto.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (C) 2015-2017, STMicroelectronics - All Rights Reserved
+ *
+ * SPDX-License-Identifier:	GPL-2.0+	BSD-3-Clause
+ */
+
+#define CPU_STMP32MP15x	0x500
+
+/* return CPU_STMP32MPxx constants */
+u32 get_cpu_type(void);
+
+#define CPU_REVA	0x1000
+#define CPU_REVB	0x2000
+
+/* return CPU_REV constants */
+u32 get_cpu_rev(void);