iio: accel: adxl380: fix handling of unavailable "INT1" interrupt

iio: accel: adxl380: fix handling of unavailable "INT1" interrupt

fwnode_irq_get_byname() returns a negative value on failure; if a negative
value is returned, use it as `err` argument for dev_err_probe().
While at it, add a missing trailing newline to the dev_err_probe() error
message.

Fixes: df36de13677a ("iio: accel: add ADXL380 driver")
Signed-off-by: Francesco Lavra <flavra@baylibre.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>