iio:adc:nau7802: Use IRQF_NO_AUTOEN instead of request then disable

Whilst a race during interrupt enabling is probably not a problem,
it is better to not enable the interrupt at all.  The new
IRQF_NO_AUTOEN flag allows us to do that.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Reviewed-by: Barry Song <song.bao.hua@hisilicon.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Link: https://lore.kernel.org/r/20210402184544.488862-4-jic23@kernel.org