fix(tree): correct some typos

found using codespell (https://github.com/codespell-project/codespell).

Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Change-Id: I1bfa797e3460adddeefa916bb68e22beddaf6373
diff --git a/lib/optee/optee_utils.c b/lib/optee/optee_utils.c
index 25272fc..6641db9 100644
--- a/lib/optee/optee_utils.c
+++ b/lib/optee/optee_utils.c
@@ -180,7 +180,7 @@
 
 	/*
 	 * Update "pc" value which should comes from pager image. After the
-	 * header image is parsed, it will be unuseful, and the actual
+	 * header image is parsed, it will be useless, and the actual
 	 * execution image after BL31 is pager image.
 	 */
 	header_ep->pc =	pager_image_info->image_base;