ARM: dts: s5pv210: remove dedicated 'audio-subsystem' node

The 'audio-subsystem' node is an artificial creation, not representing
real hardware.  The hardware is described by its nodes - AUDSS clock
controller and I2S0.

Remove the 'audio-subsystem' node along with its undocumented compatible
to fix dtbs_check warnings like:

  audio-subsystem: $nodename:0: 'audio-subsystem' does not match '^([a-z][a-z0-9\\-]+-bus|bus|soc|axi|ahb|apb)(@[0-9a-f]+)?$'
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Tested-by: Jonathan Bakker <xc-racer2@live.ca>
Link: https://lore.kernel.org/r/20200907161141.31034-9-krzk@kernel.org

arch/arm/boot/dts/s5pv210.dtsi

@@ -223,12 +223,6 @@ i2c2: i2c@e1a00000 {
 			status = "disabled";
 		};
 
-		audio-subsystem {
-			compatible = "samsung,s5pv210-audss", "simple-bus";
-			#address-cells = <1>;
-			#size-cells = <1>;
-			ranges;
-
 		clk_audss: clock-controller@eee10000 {
 			compatible = "samsung,s5pv210-audss-clock";
 			reg = <0xeee10000 0x1000>;
@@ -260,7 +254,6 @@ i2s0: i2s@eee30000 {
 			#sound-dai-cells = <0>;
 			status = "disabled";
 		};
-		};
 
 		i2s1: i2s@e2100000 {
 			compatible = "samsung,s3c6410-i2s";