Revert previous fix for when the IAX2 channel goes funky (that's the technical term). This is causing legit calls to be prematurely hung up. (issue #9600 reported by justdave)

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.2@62037 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_iax2.c

@@ -3164,8 +3164,12 @@ static int iax2_setoption(struct ast_channel *c, int option, void *data, int dat
 
 static struct ast_frame *iax2_read(struct ast_channel *c) 
 {
-	ast_log(LOG_NOTICE, "I should never be called! Hanging up.\n");
-	return NULL;
+	static struct ast_frame null_frame = {
+		AST_FRAME_NULL,
+	};
+
+	ast_log(LOG_NOTICE, "I should never be called!\n");
+	return &null_frame;
 }
 
 static int iax2_start_transfer(unsigned short callno0, unsigned short callno1)