dt-bindings: PCI: microchip: increase number of items in ranges property

Increase the number of items in the ranges property to allow up to 3
ranges. For example a prefetchable range, a non-prefetchable range
and an IO range, depending on configuration.

Signed-off-by: Valentina Fernandez <valentina.fernandezalanis@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240327-debunk-perky-f5514ca332be@spud
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>