Fix ambiguous overload for empty ip address for ESP's

src/TinyGsmClientBG96.h

@@ -462,7 +462,7 @@ public:
     if (res != 1)
       return false;
 
-    return localIP() != 0;
+    return localIP() != IPAddress(0,0,0,0);
   }
 
   /*

src/TinyGsmClientM95.h

@@ -500,7 +500,7 @@ public:
     if (res != 1)
       return false;
 
-    return localIP() != 0;
+    return localIP() != IPAddress(0,0,0,0);
   }
 
   /*

src/TinyGsmClientMC60.h

@@ -528,7 +528,7 @@ public:
     if (res != 1)
       return false;
 
-    return localIP() != 0;
+    return localIP() != IPAddress(0,0,0,0);
   }
 
   /*

src/TinyGsmClientUBLOX.h

@@ -598,7 +598,7 @@ public:
     if (res != 1)
       return false;
 
-    return localIP() != 0;
+    return localIP() != IPAddress(0,0,0,0);
   }
 
   /*