Cleanup unused function

Change-Id: Ic0895e1973b3879b2a63f7e0b888e9a0480be6f3
diff --git a/native/src/unigram_dictionary.cpp b/native/src/unigram_dictionary.cpp
index 8eb5a97..7ff2f4a 100644
--- a/native/src/unigram_dictionary.cpp
+++ b/native/src/unigram_dictionary.cpp
@@ -253,12 +253,6 @@
     mProximityInfo = proximityInfo;
 }
 
-static inline void registerNextLetter(unsigned short c, int *nextLetters, int nextLettersSize) {
-    if (c < nextLettersSize) {
-        nextLetters[c]++;
-    }
-}
-
 // TODO: We need to optimize addWord by using STL or something
 // TODO: This needs to take an const unsigned short* and not tinker with its contents
 bool UnigramDictionary::addWord(unsigned short *word, int length, int frequency) {