hwmon: (chipcap2) fix uninitialized variable in cc2_get_reg_val()

The reg_val variable in cc2_get_reg_val() might be used without a known
value if cc2_read_reg() fails. That leads to a useless data conversion
because the returned error means the read operation failed and the data is
not relevant.

That makes its initial value irrelevant as well, so skip the data
conversion instead. If no error happens, a value is assigned to reg_val
and the data conversion is required.
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-hwmon/294e4634-89d4-415e-a723-b208d8770d7c@gmail.com/T/#tSigned-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://lore.kernel.org/r/20240207-chipcap2_init_vars-v1-1-08cafe43e20e@gmail.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/chipcap2.c

@@ -324,7 +324,9 @@ static int cc2_get_reg_val(struct cc2_data *data, u8 reg, long *val)
 	int ret;
 
 	ret = cc2_read_reg(data, reg, &reg_val);
-	*val = cc2_rh_convert(reg_val);
+	if (!ret)
+		*val = cc2_rh_convert(reg_val);
+
 	cc2_disable(data);
 
 	return ret;