ARM: dts: stm32: update stm32mp151 for remote proc synchronization support

Two backup registers are used to store the Cortex-M4 state and the resource
table address.
Declare the tamp node and add associated properties in m4_rproc node
to allow Linux to attach to a firmware loaded by the first boot stages.

Associated driver implementation is available in commit 9276536f
("remoteproc: stm32: Parse syscon that will manage M4 synchronisation").
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32mp151.dtsi

@@ -1573,6 +1573,11 @@ i2c6: i2c@5c009000 {
 			status = "disabled";
 		};
 
+		tamp: tamp@5c00a000 {
+			compatible = "st,stm32-tamp", "syscon";
+			reg = <0x5c00a000 0x400>;
+		};
+
 		/*
 		 * Break node order to solve dependency probe issue between
 		 * pinctrl and exti.
@@ -1749,6 +1754,8 @@ m4_rproc: m4@10000000 {
 			st,syscfg-holdboot = <&rcc 0x10C 0x1>;
 			st,syscfg-tz = <&rcc 0x000 0x1>;
 			st,syscfg-pdds = <&pwr_mcu 0x0 0x1>;
+			st,syscfg-rsc-tbl = <&tamp 0x144 0xFFFFFFFF>;
+			st,syscfg-m4-state = <&tamp 0x148 0xFFFFFFFF>;
 			status = "disabled";
 		};
 	};