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/plat/marvell/armada/a8k/common/plat_pm.c b/plat/marvell/armada/a8k/common/plat_pm.c
index 9ea9276..f08f08a 100644
--- a/plat/marvell/armada/a8k/common/plat_pm.c
+++ b/plat/marvell/armada/a8k/common/plat_pm.c
@@ -423,7 +423,7 @@
 	} else
 #endif
 	{
-		/* proprietary CPU ON exection flow */
+		/* proprietary CPU ON execution flow */
 		plat_marvell_cpu_on(mpidr);
 	}
 	return 0;