dt-bindings: iio: accel: bma255: Add interrupt-names

The binding already allows specifying both interrupt pins, but there
is currently no way to describe a board where (for whatever reason)
only INT2 is connected. Make it possible to use "interrupt-names"
to make it explicit which interrupt pin is meant in the interrupts.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210802155657.102766-2-stephan@gerhold.net


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>