dt-bindings: PCI: brcm,iproc-pcie: Fix example indentation

The example's indentation is off. While fixing this, the 'bus' node
is unnecessary and can be dropped. It is also preferred to split up
unrelated examples to their own entries.

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230926155351.31117-1-robh@kernel.org


Signed-off-by: Rob Herring <robh@kernel.org>