dt-bindings: iio: accel: bma255: Add bosch,bmc156_accel

dt-bindings: iio: accel: bma255: Add bosch,bmc156_accel

BMC156 is very smilar to BMC150, but it has only one accelerometer
interrupt pin. It would make sense if only INT1 was exposed but someone
at Bosch decided to only have an INT2 pin.

In this case, it does not make sense if the first interrupt pin is
treated as INT1 (since that pin does not exist). Add a note to the
bindings that the first interrupt pin is treated as INT2 for BMC156.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20210802155657.102766-3-stephan@gerhold.net
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>