dt-bindings: PCI: altera: msi: Convert to YAML

Convert the devicetree bindings for the Altera PCIe MSI controller
from text to YAML.

Link: https://lore.kernel.org/linux-pci/20240717181756.2177553-1-matthew.gerlach@linux.intel.com


Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
[kwilczynski: remove unused msi0 label]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>