dt-bindings: serial: pl011: Add optional power-domains property

AMD/Xilinx Versal device serial IP has its own power domain,
so add an optional property to describe it.

Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250129095013.2145580-1-manikanta.guntupalli@amd.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>