arm64: dts: ti: k3-j721e-main: Add missing power-domains for smmu

Add power-domains entry for smmu, so that the it is accessible as long
as the driver is active. Without this device shutdown is throwing the
below warning:
"[   44.736348] arm-smmu-v3 36600000.smmu: failed to clear cr0"

Reported-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>