iio: mma8452: Use correct type for return variable in IRQ handler

The IRQ handler's return type is irqreturn_t. The mma8452 uses a variable
to store the return value, but the variable is of type int. Change this to
irqreturn_t. This makes it easier to verify that the code is correct.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20211101102734.32291-1-lars@metafoo.de


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