ARC: [plat-arcfpga] DT arc-uart bindings change: "baud" => "current-speed"

Per Grant's review comment - driver changes via tty tree

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/boot/dts/angel4.dts b/arch/arc/boot/dts/angel4.dts
index 4c188d5..bae4f93 100644
--- a/arch/arc/boot/dts/angel4.dts
+++ b/arch/arc/boot/dts/angel4.dts
@@ -48,7 +48,7 @@
 			reg = <0xc0fc1000 0x100>;
 			interrupts = <5>;
 			clock-frequency = <80000000>;
-			baud = <115200>;
+			current-speed = <115200>;
 			status = "okay";
 		};
 	};