dt-bindings: PCI: brcmstb: Update bindings for PCIe on BCM2712

Update PCIe controller bindings with BCM2712 support.

Signed-off-by: Stanimir Varbanov <svarbanov@suse.de>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Tested-by: Ivan T. Ivanov <iivanov@suse.de>
Link: https://lore.kernel.org/r/20250224083559.47645-3-svarbanov@suse.de


[kwilczynski: commit log]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>