ns16550: unify serial_x86

Unify serial_x86, and use the generic binding.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/dts/serial.dtsi b/arch/x86/dts/serial.dtsi
index 6865eed..54c3faf 100644
--- a/arch/x86/dts/serial.dtsi
+++ b/arch/x86/dts/serial.dtsi
@@ -1,6 +1,6 @@
 / {
 	serial: serial {
-		compatible = "x86-uart";
+		compatible = "ns16550";
 		reg = <0x3f8 8>;
 		reg-shift = <0>;
 		clock-frequency = <1843200>;