Remove old TODOs for non-standard ipv4 format support

Signed-off-by: Patrick Roncagliolo <ronca.pat@gmail.com>

cores/arduino/IPAddress.cpp

@@ -45,8 +45,6 @@ IPAddress::IPAddress(const uint8_t *address)
 
 bool IPAddress::fromString(const char *address)
 {
-    // TODO: add support for "a", "a.b", "a.b.c" formats
-
     uint16_t acc = 0; // Accumulator
     uint8_t dots = 0;