iio: light: opt3001: fix missing state reset on timeout
Currently in the function opt3001_get_processed(), there is a check
that directly returns -ETIMEDOUT if the conversion IRQ times out,
completely bypassing the err label, leaving ok_to_ignore_lock
permanently true, potentially breaking the device's falling threshold
interrupt detection.
Assign -ETIMEDOUT to the return variable and jump to the error label
to ensure ok_to_ignore_lock is properly reset.