The clang-analyzer reported a warning: "Value stored to 'ret'
is never read".

Fix the return value check if devm_krealloc() fails to resize
ams_channels.

Fixes: d5c70627 ("iio: adc: Add Xilinx AMS driver")
Signed-off-by: Marco Pagani <marpagan@redhat.com>
Acked-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/20221125113112.219290-1-marpagan@redhat.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>