hwmon: (pmbus) Update documentation to not use .probe_new() any more

Since commit 03c835f4 ("i2c: Switch .probe() to not take an id
parameter") .probe() is the recommended callback to implement an i2c
driver (again). Reflect this in the documentation and don't mention
.probe_new() which will be dropped soon.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230627064948.593804-1-u.kleine-koenig@pengutronix.deSigned-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/pmbus.rst

@@ -163,7 +163,7 @@ Emerson DS1200 power modules might look as follows::
 	.driver = {
 		   .name = "ds1200",
 		   },
-	.probe_new = ds1200_probe,
+	.probe = ds1200_probe,
 	.id_table = ds1200_id,
   };