Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/block/blk-core.c b/block/blk-core.c
index e0a0623..071ae6d 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1184,7 +1184,7 @@
 
 /*
  * Attempts to merge with the plugged list in the current process. Returns
- * true if merge was succesful, otherwise false.
+ * true if merge was successful, otherwise false.
  */
 static bool attempt_plug_merge(struct task_struct *tsk, struct request_queue *q,
 			       struct bio *bio)