arm64: dts: ti: k3-j721e-main: Move secure proxy and smmu under main_navss

Secure proxy (NAVSS0_SEC_PROXY0) and smmu (NAVSS0_TCU) is part of the
Navigator Subsystem.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>