riscv: dts: microchip: add specific compatible for mpfs pdma

Add specific compatible for PolarFire SoC for The SiFive PDMA driver

Reviewed-by: Conor Dooley <[e-mail]>
Signed-off-by: Shravan Chippa <[e-mail]>
Signed-off-by: Conor Dooley <[e-mail]>

arch/riscv/boot/dts/microchip/mpfs.dtsi

···
 		};
 
 		pdma: dma-controller@3000000 {
-			compatible = "sifive,fu540-c000-pdma", "sifive,pdma0";
+			compatible = "microchip,mpfs-pdma", "sifive,pdma0";
 			reg = <0x0 0x3000000 0x0 0x8000>;
 			interrupt-parent = <&plic>;
 			interrupts = <5 6>, <7 8>, <9 10>, <11 12>;