ARM: dts: stih4xx: Add missing #sound-dai-cells

dtc now gives the following warnings:

arch/arm/boot/dts/stih410-b2120.dtb: Warning (sound_dai_property): /soc/sound/simple-audio-card,dai-link@0/codec: Missing property '#sound-dai-cells' in node /soc/sti-display-subsystem/sti-hdmi@8d04000 or bad phandle (referred from sound-dai[0])
arch/arm/boot/dts/stih407-b2120.dtb: Warning (sound_dai_property): /soc/sound/simple-audio-card,dai-link@0/codec: Missing property '#sound-dai-cells' in node /soc/sti-display-subsystem/sti-hdmi@8d04000 or bad phandle (referred from sound-dai[0])
arch/arm/boot/dts/stih410-b2260.dtb: Warning (sound_dai_property): /soc/sound/simple-audio-card,dai-link@0/codec: Missing property '#sound-dai-cells' in node /soc/sti-display-subsystem/sti-hdmi@8d04000 or bad phandle (referred from sound-dai[0])

Add the missing #sound-dai-cells property.

Cc: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>