ARM: dts: imx: Add missing #sound-dai-cells for sgtl5000 codec

dtc now warns about missing #sound-dai-cells:

arch/arm/boot/dts/imx6ul-geam.dtb: Warning (sound_dai_property): /sound/simple-audio-card,codec: Missing property '#sound-dai-cells' in node /soc/aips-bus@2100000/i2c@21a0000/codec@a or bad phandle (referred from sound-dai[0])
arch/arm/boot/dts/imx6ul-isiot-emmc.dtb: Warning (sound_dai_property): /sound/simple-audio-card,codec: Missing property '#sound-dai-cells' in node /soc/aips-bus@2100000/i2c@21a0000/codec@a or bad phandle (referred from sound-dai[0])
arch/arm/boot/dts/imx6ul-isiot-nand.dtb: Warning (sound_dai_property): /sound/simple-audio-card,codec: Missing property '#sound-dai-cells' in node /soc/aips-bus@2100000/i2c@21a0000/codec@a or bad phandle (referred from sound-dai[0])

Lots of i.MX boards use the SGTL5000 codec, but not all get the warning
because only some reference the codec with "sound-dai" property. However,
the codec should always provide #sound-dai-cells regardless, so fix all
the occurrences.

Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>