iio: pressure: bmp280: Fix NULL pointer exception

commit 85dfb43b upstream.

The bmp085 EOC IRQ support is optional, but the driver's common probe
function queries the IRQ properties whether or not it exists, which
can trigger a NULL pointer exception. Avoid any exception by making
the query conditional on the possession of a valid IRQ.

Fixes: aae95394

 ("iio: pressure: bmp280: add support for BMP085 EOC interrupt")
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230811155829.51208-1-phil@raspberrypi.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>