iio: adis_buffer: check return value on page change

On the trigger handler, we might need to change the device page. Hence,
we should check the return value from 'spi_write()' and act accordingly.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>
Link: https://lore.kernel.org/r/20210422101911.135630-5-nuno.sa@analog.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>