ARM: dts: stm32: add hdmi audio support to stm32mp157a-dk1 board

Add HDMI audio support through Sil9022 HDMI transceiver
on stm32mp157a-dk1 board.
Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32mp157a-dk1.dts

@@ -93,7 +93,7 @@ sound {
 			"Playback" , "MCLK",
 			"Capture" , "MCLK",
 			"MICL" , "Mic Bias";
-		dais = <&sai2a_port &sai2b_port>;
+		dais = <&sai2a_port &sai2b_port &i2s2_port>;
 		status = "okay";
 	};
 };
@@ -174,6 +174,7 @@ hdmi-transmitter@39 {
 		reset-gpios = <&gpioa 10 GPIO_ACTIVE_LOW>;
 		interrupts = <1 IRQ_TYPE_EDGE_FALLING>;
 		interrupt-parent = <&gpiog>;
+		#sound-dai-cells = <0>;
 		status = "okay";
 
 		ports {
@@ -186,6 +187,13 @@ sii9022_in: endpoint {
 					remote-endpoint = <&ltdc_ep0_out>;
 				};
 			};
+
+			port@3 {
+				reg = <3>;
+				sii9022_tx_endpoint: endpoint {
+					remote-endpoint = <&i2s2_endpoint>;
+				};
+			};
 		};
 	};
 
@@ -371,6 +379,23 @@ watchdog {
 	};
 };
 
+&i2s2 {
+	clocks = <&rcc SPI2>, <&rcc SPI2_K>, <&rcc PLL3_Q>, <&rcc PLL3_R>;
+	clock-names = "pclk", "i2sclk", "x8k", "x11k";
+	pinctrl-names = "default", "sleep";
+	pinctrl-0 = <&i2s2_pins_a>;
+	pinctrl-1 = <&i2s2_pins_sleep_a>;
+	status = "okay";
+
+	i2s2_port: port {
+		i2s2_endpoint: endpoint {
+			remote-endpoint = <&sii9022_tx_endpoint>;
+			format = "i2s";
+			mclk-fs = <256>;
+		};
+	};
+};
+
 &ipcc {
 	status = "okay";
 };