kernel: Reformat code using clang-format (#347)

* The coding format is too messy, reformat to improve readability
  and get closer to Linux kernel coding style.

* While at it, update .clang-format file to linux-mainline state.

kernel/manager.h

@@ -21,7 +21,8 @@ static inline bool ksu_is_manager_uid_valid()
 
 static inline bool is_manager()
 {
-	return unlikely(ksu_is_any_manager(ksu_current_uid()) || ksu_manager_uid == ksu_current_uid());
+	return unlikely(ksu_is_any_manager(ksu_current_uid()) ||
+			ksu_manager_uid == ksu_current_uid());
 }
 
 static inline uid_t ksu_get_manager_uid()