arm64: dts: ti: k3-j721e: Update the power domain cells

Update the power-domain cells to 2 and mark all devices as
exclusive. Main uart 0 is the debug console for processor boards
and it is used by different software entities like u-boot, atf,
linux simultaneously. So just mark main_uart0 as shared device
for common processor board.

Reviewed-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>