Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index e99f6cd1..9109049 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -150,7 +150,7 @@
 {
 	/*
 	 * We need to use MAX_NUMNODES instead of NODE_DATA(0)->node_id
-	 *  because in some case like Node0 doesnt have RAM installed
+	 *  because in some case like Node0 doesn't have RAM installed
 	 *  low ram will be on Node1
 	 * Use MAX_NUMNODES will make sure all ranges in early_node_map[]
 	 *  will be used instead of only Node0 related