dt-bindings: soc: ti: ti,j721e-system-controller: Add PCIe ctrl property

Add a pattern property for pcie-ctrl which can be part of this controller.

Signed-off-by: Andrew Davis <afd@ti.com>
[j-choudhary@ti.com: Change description and add example]
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Reviewed-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250402113201.151195-2-j-choudhary@ti.com


Signed-off-by: Nishanth Menon <nm@ti.com>