iio: pressure: zpa2326: report interrupted case as failure

If the timeout-case prints a warning message then probably the interrupted
case should also. Further, wait_for_completion_interruptible_timeout()
returns long not int.

Fixes: commit 03b262f2 ("iio:pressure: initial zpa2326 barometer support")
Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>