arm64: dts: st: set RIFSC as an access controller on stm32mp21x platforms

Similarly to stm32mp23x/25x platforms, the RIFSC is a firewall
controller. Declare it as an access controller, keep the "simple-bus"
compatible in case CONFIG_STM32_FIREWALL is not set and update the
child nodes.

Signed-off-by: Gatien Chevallier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexandre Torgue <[e-mail]>

arch/arm64/boot/dts/st/stm32mp211.dtsi

···
 		#size-cells = <2>;
 
 		rifsc: bus@42080000 {
-			compatible = "simple-bus";
+			compatible = "st,stm32mp21-rifsc", "simple-bus";
 			reg = <0x42080000 0x0 0x1000>;
 			ranges;
 			dma-ranges;
 			#address-cells = <1>;
 			#size-cells = <2>;
+			#access-controller-cells = <1>;
 
 			usart2: serial@400e0000 {
 				compatible = "st,stm32h7-uart";
 				reg = <0x400e0000 0x0 0x400>;
 				interrupts = <GIC_SPI 102 IRQ_TYPE_LEVEL_HIGH>;
 				clocks = <&ck_flexgen_08>;
+				access-controllers = <&rifsc 32>;
 				status = "disabled";
 			};
 		};