Move sound node outside soc node and sti_sasg_codec node
as child of syscfg_core node.
This allows to fix the following warning when compiling
dtb with W=1 option:

arch/arm/boot/dts/stih407-b2120.dtb: Warning (unit_address_vs_reg):
Node /soc/sound/simple-audio-card,dai-link@0 has a unit name, but no reg property
arch/arm/boot/dts/stih407-b2120.dtb: Warning (unit_address_vs_reg):
Node /soc/sound/simple-audio-card,dai-link@1 has a unit name, but no reg property
arch/arm/boot/dts/stih407-b2120.dtb: Warning (unit_address_vs_reg):
Node /soc/sound/simple-audio-card,dai-link@2 has a unit name, but no reg property
arch/arm/boot/dts/stih410-b2120.dtb: Warning (simple_bus_reg):
Node /soc/sti-sasg-codec missing or empty reg/ranges property

arch/arm/boot/dts/stih410-b2120.dtb: Warning (unit_address_vs_reg):
Node /soc/sound/simple-audio-card,dai-link@0 has a unit name, but no reg property
arch/arm/boot/dts/stih410-b2120.dtb: Warning (unit_address_vs_reg):
Node /soc/sound/simple-audio-card,dai-link@1 has a unit name, but no reg property
arch/arm/boot/dts/stih410-b2120.dtb: Warning (unit_address_vs_reg):
Node /soc/sound/simple-audio-card,dai-link@2 has a unit name, but no reg property
arch/arm/boot/dts/stih407-b2120.dtb: Warning (simple_bus_reg):
Node /soc/sound missing or empty reg/ranges property
arch/arm/boot/dts/stih410-b2120.dtb: Warning (simple_bus_reg):
Node /soc/sti-sasg-codec missing or empty reg/ranges property

arch/arm/boot/dts/stih410-b2260.dtb: Warning (unit_address_vs_reg):
Node /soc/sound/simple-audio-card,dai-link@0 has a unit name, but no reg property
arch/arm/boot/dts/stih410-b2260.dtb: Warning (simple_bus_reg):
Node /soc/sti-sasg-codec missing or empty reg/ranges property
arch/arm/boot/dts/stih410-b2260.dtb: Warning (simple_bus_reg):
Node /soc/sound missing or empty reg/ranges property

arch/arm/boot/dts/stih418-b2199.dtb: Warning (simple_bus_reg):
Node /soc/sti-sasg-codec missing or empty reg/ranges property
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>