Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 3f7ec9e..3cb7f07 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -3061,7 +3061,7 @@
 
 	/*
 	 * if *imbalance is less than the average load per runnable task
-	 * there is no gaurantee that any tasks will be moved so we'll have
+	 * there is no guarantee that any tasks will be moved so we'll have
 	 * a think about bumping its value to force at least one task to be
 	 * moved
 	 */