iio:magnetometer:bmc150_magn: expand mutex in trigger_handler

Keep the mutex locked, until the content of data->buffer has been pushed
out.
Signed-off-by: Hartmut Knaack <knaack.h@gmx.de>
Acked-by: Irina Tirdea <irina.tirdea@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/magnetometer/bmc150_magn.c

@@ -664,7 +664,6 @@ static irqreturn_t bmc150_magn_trigger_handler(int irq, void *p)
 
 	mutex_lock(&data->mutex);
 	ret = bmc150_magn_read_xyz(data, data->buffer);
-	mutex_unlock(&data->mutex);
 	if (ret < 0)
 		goto err;
 
@@ -672,6 +671,7 @@ static irqreturn_t bmc150_magn_trigger_handler(int irq, void *p)
 					   pf->timestamp);
 
 err:
+	mutex_unlock(&data->mutex);
 	iio_trigger_notify_done(indio_dev->trig);
 
 	return IRQ_HANDLED;