[pretty] apply clang-format-9 (#5761)

src/core/backbone_router/ndproxy_table.hpp

@@ -264,7 +264,7 @@ private:
         void           Advance(void);
         void           operator++(void) { Advance(); }
         void           operator++(int) { Advance(); }
-        const NdProxy &operator*(void) const { return *mCurrent; }
+        const NdProxy &operator*(void)const { return *mCurrent; }
         bool           operator==(const Iterator &aOther) const { return mCurrent == aOther.mCurrent; }
         bool           operator!=(const Iterator &aOther) const { return !(*this == aOther); }
         NdProxy *      operator->(void) { return mCurrent; }

src/core/common/settings.hpp

@@ -916,7 +916,7 @@ public:
          * @returns A reference to the `ChildInfo` entry currently pointed by the iterator.
          *
          */
-        const ChildInfo &operator*(void) const { return mChildInfo; }
+        const ChildInfo &operator*(void)const { return mChildInfo; }
 
         /**
          * This method overloads operator `==` to evaluate whether or not two iterator instances are equal.

src/core/thread/topology.hpp

@@ -831,7 +831,7 @@ public:
          * @returns A reference to the `Ip6::Address` entry currently pointed by the iterator.
          *
          */
-        const Ip6::Address &operator*(void) const { return *GetAddress(); }
+        const Ip6::Address &operator*(void)const { return *GetAddress(); }
 
         /**
          * This method overloads operator `==` to evaluate whether or not two `Iterator` instances are equal.