sensor: adltc2990: separate function return values

This commit reworks the adltc2990_fetch_property_value function
to pass its result through a variable pointer instead of direct return.
This is done in part to separate the errno value being return in the
default case of the switch from the result of the function, but also
to make it easier the fix a Coverity issue regarding the unhandled
return values of i2c reads.

Signed-off-by: Benjamin Björnsson <benjamin.bjornsson@gmail.com>
1 file changed