iio: adc: ti-ads1298: Add NULL check in ads1298_init

devm_kasprintf() can return a NULL pointer on failure. A check on the
return value of such a call in ads1298_init() is missing. Add it.

Fixes: 00ef7708 ("iio: adc: ti-ads1298: Add driver")
Signed-off-by: Charles Han <hanchunchao@inspur.com>
Link: https://patch.msgid.link/20241118090208.14586-1-hanchunchao@inspur.com


Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>