ARC: nSIM_700: switch to DW UART usage

Switch nsim_700_defconfig to dwuart for consistent uart settings
for all nSIM configurations.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/boot/dts/nsim_700.dts

@@ -14,11 +14,11 @@ / {
 	interrupt-parent = <&core_intc>;
 
 	chosen {
-		bootargs = "earlycon=arc_uart,mmio32,0xc0fc1000,115200n8 console=ttyARC0,115200n8 print-fatal-signals=1";
+		bootargs = "earlycon=uart8250,mmio32,0xf0000000,115200n8 console=ttyS0,115200n8 print-fatal-signals=1";
 	};
 
 	aliases {
-		serial0 = &arcuart0;
+		serial0 = &uart0;
 	};
 
 	fpga {
@@ -41,13 +41,15 @@ core_intc: interrupt-controller {
 			#interrupt-cells = <1>;
 		};
 
-		arcuart0: serial@c0fc1000 {
-			compatible = "snps,arc-uart";
-			reg = <0xc0fc1000 0x100>;
-			interrupts = <5>;
-			clock-frequency = <80000000>;
-			current-speed = <115200>;
-			status = "okay";
+		uart0: serial@f0000000 {
+			compatible = "ns16550a";
+			reg = <0xf0000000 0x2000>;
+			interrupts = <24>;
+			clock-frequency = <50000000>;
+			baud = <115200>;
+			reg-shift = <2>;
+			reg-io-width = <4>;
+			no-loopback-test = <1>;
 		};
 
 		ethernet@c0fc2000 {

arch/arc/configs/nsim_700_defconfig

@@ -41,8 +41,12 @@ CONFIG_LXT_PHY=y
 # CONFIG_INPUT_MOUSE is not set
 # CONFIG_SERIO is not set
 # CONFIG_LEGACY_PTYS is not set
-CONFIG_SERIAL_ARC=y
-CONFIG_SERIAL_ARC_CONSOLE=y
+CONFIG_SERIAL_8250=y
+CONFIG_SERIAL_8250_CONSOLE=y
+CONFIG_SERIAL_8250_NR_UARTS=1
+CONFIG_SERIAL_8250_RUNTIME_UARTS=1
+CONFIG_SERIAL_8250_DW=y
+CONFIG_SERIAL_OF_PLATFORM=y
 # CONFIG_HW_RANDOM is not set
 # CONFIG_HWMON is not set
 # CONFIG_HID is not set