hwmon: (lm90) Mark alert as broken for MAX6654

Experiments with MAX6654 show that its alert function is broken,
similar to other chips supported by the lm90 driver. Mark it accordingly.

Fixes: 229d495d

 ("hwmon: (lm90) Add max6654 support to lm90 driver")
Cc: Josh Lehan <krellan@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>