dt-bindings:iio:adc:nxp,lpc3220-adc yaml conversion

Renamed to remove the wild cards.  These go wrong far too often so
in general preferred to use the name of a specific part.  As this
binding only provides one compatible, I went with that.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Gregory Clement <gregory.clement@bootlin.com>
Link: https://lore.kernel.org/r/20200909175946.395313-11-jic23@kernel.org