tracing/hwlat: Fix a few trivial nits

Update the source file name in the comments, and fix a grammatical
error.

Link: http://lkml.kernel.org/r/157073346821.17189.8946944856026592247.stgit@srivatsa-ubuntuSigned-off-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace_hwlat.c

 // SPDX-License-Identifier: GPL-2.0
 /*
- * trace_hwlatdetect.c - A simple Hardware Latency detector.
+ * trace_hwlat.c - A simple Hardware Latency detector.
  *
  * Use this tracer to detect large system latencies induced by the behavior of
  * certain underlying system hardware or firmware, independent of Linux itself.
@@ -279,7 +279,7 @@ static void move_to_next_cpu(void)
 		return;
 	/*
 	 * If for some reason the user modifies the CPU affinity
-	 * of this thread, than stop migrating for the duration
+	 * of this thread, then stop migrating for the duration
 	 * of the current test.
 	 */
 	if (!cpumask_equal(current_mask, current->cpus_ptr))