Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 321fc74..a2acaf8 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -724,7 +724,7 @@
 			       pfn);
 			dump_page(page);
 #endif
-			/* Becasue we don't have big zone->lock. we should
+			/* Because we don't have big zone->lock. we should
 			   check this again here. */
 			if (page_count(page)) {
 				not_managed++;