iio:adc:ad799x: Only expose event interface when IRQ is available

an IRQ is necessary to handle the ALERT condition; without
IRQ, the IIO event interface serves no purpose

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
1 file changed