iio: ak8975: minor fixes

Fixes code duplication, return of function.
Check client->irq properly when setting up optional irq handler.

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
1 file changed