Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 92b6e1e..a4969b4 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -80,7 +80,7 @@
  * skip the latency if the sequence has changed - some other section
  * did a maximum and could disturb our measurement with serial console
  * printouts, etc. Truly coinciding maximum latencies should be rare
- * and what happens together happens separately as well, so this doesnt
+ * and what happens together happens separately as well, so this doesn't
  * decrease the validity of the maximum found:
  */
 static __cacheline_aligned_in_smp	unsigned long max_sequence;