hwmon: (pmbus/ltc2978) Add support for LT717x - docs

Add LT7170 and LT7171 to compatible devices of LTC2978.

Co-developed-by: Cherrence Sarip <cherrence.sarip@analog.com>
Signed-off-by: Cherrence Sarip <cherrence.sarip@analog.com>
Signed-off-by: Kim Seer Paller <kimseer.paller@analog.com>
Link: https://lore.kernel.org/r/20250317-hwmon-next-v1-1-da0218c38197@analog.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>