schema REFACTOR remove lyext_substmt2str() macro

It was just duplicating what ly_stmt2str() macro does.
diff --git a/src/parser_yang.c b/src/parser_yang.c
index cae5398..9649002 100644
--- a/src/parser_yang.c
+++ b/src/parser_yang.c
@@ -894,7 +894,7 @@
     enum ly_stmt kw;
 
     if (*value) {
-        LOGVAL_PARSER(ctx, LY_VCODE_DUPSTMT, lyext_substmt2str(substmt));
+        LOGVAL_PARSER(ctx, LY_VCODE_DUPSTMT, ly_stmt2str(substmt));
         return LY_EVALID;
     }
 
@@ -910,7 +910,7 @@
             LY_CHECK_RET(parse_ext(ctx, word, word_len, substmt, substmt_index, exts));
             break;
         default:
-            LOGVAL_PARSER(ctx, LY_VCODE_INCHILDSTMT, ly_stmt2str(kw), lyext_substmt2str(substmt));
+            LOGVAL_PARSER(ctx, LY_VCODE_INCHILDSTMT, ly_stmt2str(kw), ly_stmt2str(substmt));
             return LY_EVALID;
         }
     }
@@ -1266,7 +1266,7 @@
             LY_CHECK_RET(parse_ext(ctx, word, word_len, substmt, LY_ARRAY_COUNT(*texts) - 1, exts));
             break;
         default:
-            LOGVAL_PARSER(ctx, LY_VCODE_INCHILDSTMT, ly_stmt2str(kw), lyext_substmt2str(substmt));
+            LOGVAL_PARSER(ctx, LY_VCODE_INCHILDSTMT, ly_stmt2str(kw), ly_stmt2str(substmt));
             return LY_EVALID;
         }
     }
@@ -1308,7 +1308,7 @@
             LY_CHECK_RET(parse_ext(ctx, word, word_len, substmt, LY_ARRAY_COUNT(*qnames) - 1, exts));
             break;
         default:
-            LOGVAL_PARSER(ctx, LY_VCODE_INCHILDSTMT, ly_stmt2str(kw), lyext_substmt2str(substmt));
+            LOGVAL_PARSER(ctx, LY_VCODE_INCHILDSTMT, ly_stmt2str(kw), ly_stmt2str(substmt));
             return LY_EVALID;
         }
     }
@@ -2087,7 +2087,7 @@
             break;
         case LY_STMT_PATH:
             if (type->path) {
-                LOGVAL_PARSER(ctx, LY_VCODE_DUPSTMT, lyext_substmt2str(LY_STMT_PATH));
+                LOGVAL_PARSER(ctx, LY_VCODE_DUPSTMT, ly_stmt2str(LY_STMT_PATH));
                 return LY_EVALID;
             }