Fix to return -ENODEV instead of 0 if non-TSMR adc don't
support, as done elsewhere in this function.
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: NJosh Wu <josh.wu@atmel.com>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>