dt-bindings:iio:humidity:dht11 yaml conversion

The conversion is straight forward, but leaves an open question.
The compatible for this device has never had a vendor.

Harald Geyer has identified as probably being made by aosong,
but we have no current match to any of their more specific part
numbers.  As such, this is noted in the file but the
compatible doesn't include the vendor prefix.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-By: Harald Geyer <harald@ccbib.org>
Link: https://lore.kernel.org/r/20201031134110.724233-5-jic23@kernel.org