iio: light: Fix spelling mistake "regist" -> "register"

There are spelling mistakes in dev_err messages. Fix them.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://patch.msgid.link/20250228090228.679535-1-colin.i.king@gmail.com


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