arm64: dts: ti: j721e-common-proc-board: Fix sound node-name

If root-node has no reg property, the unit-address should not
be appended at the end of node-name. 'sound' node has no 'reg'
property, so remove the unit-address.

Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Jai Luthra <j-luthra@ti.com>
Link: https://lore.kernel.org/r/20220928122509.143342-1-j-choudhary@ti.com