Simplify String::remove(unsigned int)

Previously, this method calculated the length of the string from the
given index onwards. However, the other remove() method called already
contains code for this calculation, which is used when the count passed
in is too big. This means we can just pass in a very big count that is
guaranteed to point past the end of the string, shrinking the remove
method by a few bytes.

cores/arduino/WString.cpp

@@ -684,8 +684,10 @@ void String::replace(const String& find, const String& replace)
 }
 
 void String::remove(unsigned int index){
-	int count = len - index;
-	remove(index, count);
+	// Pass the biggest integer as the count. The remove method
+	// below will take care of truncating it at the end of the
+	// string.
+	remove(index, (unsigned int)-1);
 }
 
 void String::remove(unsigned int index, unsigned int count){