ARM: dts: imx: Pass #sound-dai-cells to sgtl5000

As per sgtl5000.yaml, '#sound-dai-cells' is a required property.

Pass it to fix the following schema warnings:

imx53-mba53.dtb: sgtl5000@a: '#sound-dai-cells' is a required property

Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>