hwmon: (pmbus/ltc2978) Update datasheet links

Links to datasheets are no longer valid. Provide links to product information
instead (which provides links to the datasheets and is hopefully more
persistent).

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Jean Delvare <khali@linux-fr.org>
1 file changed