If the temperature is read before the internal calibration is
completed, the driver returns -EIO. Instead it should return -EAGAIN
to encourage repeating the operation.

Note (groeck): Returning -EAGAIN to userspace may result in hard loops;
some userspace code interprets -EAGAIN as request to retry immediately.
I would prefer -ENODATA, but it turns out that the thermal subsystem only
handles -EAGAIN silently, so we'll have to stick with that.
Signed-off-by: Lars Povlsen <lars.povlsen@microchip.com>
Link: https://lore.kernel.org/r/20200903134704.8949-1-lars.povlsen@microchip.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>