arm: dts: santvend: Fix sound playback

By contrast with other iMX6-based boards (Santaro), a different audmux port
is used (3 instead of 4). So, with default settings, following errors can be
observed during playback:
    Write error: -5,Input/output error
    xrun_recovery failed: -5,Input/output error
    Transfer failed: Input/output error

Fix this problem:
 - setup AUDMUX routing suitable for SantVend;
 - adjust pinctrl for sound to enable audmux 3.

Signed-off-by: Mikhail Vanyulin <mikhail.vanyulin@rtsoft.de>

arch/arm/boot/dts/seconorth/imx6qdl-santvend.dtsi

@@ -220,7 +220,7 @@ &rtc {
 
 &sound {
 	pinctrl-names = "default";
-	pinctrl-0 = <&pinctrl_audmux4>;
+	pinctrl-0 = <&pinctrl_audmux3>;
 	status = "okay";
 
 	cpu_dai: simple-audio-card,cpu {
@@ -236,6 +236,34 @@ &ssi2 {
 	status = "okay";
 };
 
+&audmux {
+	aud3 {
+	/* setup AUDMUX for internal port 2 (3 in RefMan),
+	 * external port is 1 (2 in RefMan <-> SSI2)
+	 */
+		fsl,audmux-port = <2>;
+		fsl,port-config = <
+			IMX_AUDMUX_V2_PTCR_SYN
+			IMX_AUDMUX_V2_PDCR_RXDSEL(1)
+		>;
+	};
+
+	ssi2 {
+	/* setup AUDMUX for external port 1 (2 in RefMan <-> SSI2),
+	 * internal port is 2 (3 in RefMan)
+	 */
+		fsl,audmux-port = <1>;
+		fsl,port-config = <
+			(IMX_AUDMUX_V2_PTCR_SYN |
+			IMX_AUDMUX_V2_PTCR_TFSEL(2) |
+			IMX_AUDMUX_V2_PTCR_TCSEL(2) |
+			IMX_AUDMUX_V2_PTCR_TFSDIR |
+			IMX_AUDMUX_V2_PTCR_TCLKDIR)
+			IMX_AUDMUX_V2_PDCR_RXDSEL(2)
+		>;
+	};
+};
+
 &uart1 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_uart1_rxtx &pinctrl_uart1_rcts>;