ARM: dts: stm32: add m4 remoteproc support on STM32MP157c

Declare the M4 remote processor in a sub-node of the mlahb simple bus.
Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32mp157c.dtsi

@@ -1470,4 +1470,24 @@ i2c6: i2c@5c009000 {
 			status = "disabled";
 		};
 	};
+
+	mlahb {
+		compatible = "simple-bus";
+		#address-cells = <1>;
+		#size-cells = <1>;
+		dma-ranges = <0x00000000 0x38000000 0x10000>,
+			     <0x10000000 0x10000000 0x60000>,
+			     <0x30000000 0x30000000 0x60000>;
+
+		m4_rproc: m4@10000000 {
+			compatible = "st,stm32mp1-m4";
+			reg = <0x10000000 0x40000>,
+			      <0x30000000 0x40000>,
+			      <0x38000000 0x10000>;
+			resets = <&rcc MCU_R>;
+			st,syscfg-holdboot = <&rcc 0x10C 0x1>;
+			st,syscfg-tz = <&rcc 0x000 0x1>;
+			status = "disabled";
+		};
+	};
 };