dt-bindings: PCI: Convert fsl,mpc83xx-pcie to YAML

dt-bindings: PCI: Convert fsl,mpc83xx-pcie to YAML

Formalise the binding for the PCI controllers in the Freescale MPC8xxx
chip family. Information about PCI-X-specific properties was taken from
fsl,pci.txt. The examples were taken from mpc8315erdb.dts and
xpedite5200_xmon.dts.

Signed-off-by: J. Neuschäfer <j.ne@posteo.net>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250220-ppcyaml-pci-v3-1-ca94a4f62a85@posteo.net
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>