hwmon: (tmp421) Strengthen detect function

Not all supported chips support the entire I2C address range.
Only accept specific chips at the addresses supported by that chip.
Check for invalid values in conversion rate and status registers.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Jean Delvare <jdelvare@suse.de>

diff --cc Documentation/hwmon/tmp421
Simple merge

diff --cc drivers/hwmon/tmp421.c
Simple merge