dt-bindings:iio:accel:bosch,bma180: txt to yaml format conversion.

One question in here is whether we want to constrain the number of
interrupts.  Some parts definitely only have 1 such pin, and others
2 pins but I can not find information on the bma254.

Oleksandr's email address is bouncing so I've listed myself as
maintainer for this binding until someone else steps up.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201031184854.745828-41-jic23@kernel.org