dts: intel: cavs25: hack around awkward DT representation

Apparently, downstream drivers are allocating devices using
DT_NODELABEL(alh0) and DT_NODELABEL(alh1) on a node with compatible
intel,alh-dai. These represent something like "channels" within the
device.

This is a strange choice. It would be better to do something like have
a property with the count of "channels", or one child node per
channel.

It is also a dtc error to have duplicate node names like this, and
will be an error in Zephyr's dtlib soon.

For now, work around this representation issue by replacing it with
something equivalent that doesn't have duplicate nodes. The
representation should be addressed at some point, but not by me.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>