dt-bindings:iio:accel:fsl,mma8452: txt to yaml conversion.

Simple binding so mostly straight forward to convert.
Original binding was unclear on how many interrupts there are.
The device has two such lines, whilst I believe the driver currently
only uses one at a time.  The binding should allow both to be specified.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Martin Kepplinger <martin.kepplinger@theobroma-systems.com>
Link: https://lore.kernel.org/r/20201031184854.745828-43-jic23@kernel.org