Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 3e01121..c0851a8 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -186,7 +186,7 @@
 		goto done;
 
 	/*
-	 * try non-existant, but valid partition, which may only exist
+	 * try non-existent, but valid partition, which may only exist
 	 * after revalidating the disk, like partitioned md devices
 	 */
 	while (p > s && isdigit(p[-1]))