hwmon: (nct6775) Drop duplicate NULL check in ->init() and ->exit()

hwmon: (nct6775) Drop duplicate NULL check in ->init() and ->exit()

Since platform_device_unregister() is NULL-aware, we don't need to duplicate
this check. Remove it and fold the rest of the code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Zev Weiss <zev@bewilderbeest.net>
Link: https://lore.kernel.org/r/20220610103324.87483-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>