tracing: Fix typo in trace_seq.c

 * 

 * A write to the buffer will either succeed or fail. That is, unlike

 * sprintf() there will not be a partial write (well it may write into

 * the buffer but it wont update the pointers). This allows users to

 * the buffer but it won't update the pointers). This allows users to

 * try to write something into the trace_seq buffer and if it fails

 * they can flush it and try again.

 *