hwmon: (ads2828) Only keep data in device data structure if needed
hwmon: (ads2828) Only keep data in device data structure if needed

The variables diff_input, ext_vref, and vref_mv are only used in the probe
function and therefore don't need to be kept in the device data structure.

Reviewed-and-Tested-by: Robert Rosengren <0af6cd949ac1597dccd064c04aa240ab9ec64971@axis.com>
Signed-off-by: Guenter Roeck <ba324ca7b1c77fc20bb970d5aff6eea9377918a5@roeck-us.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs