Fix typos and misspellings

Fix a number of typos and misspellings in TF-A
documentation and comments.

Signed-off-by: David Horstmann <david.horstmann@arm.com>
Change-Id: I34c5a28c3af15f28d1ccada4d9866aee6af136ee
diff --git a/plat/common/aarch64/platform_mp_stack.S b/plat/common/aarch64/platform_mp_stack.S
index c34a4cf..c0668ea 100644
--- a/plat/common/aarch64/platform_mp_stack.S
+++ b/plat/common/aarch64/platform_mp_stack.S
@@ -14,7 +14,7 @@
 	.weak	plat_set_my_stack
 
 	/* ---------------------------------------------------------------------
-	 * When the compatility layer is disabled, the platform APIs
+	 * When the compatibility layer is disabled, the platform APIs
 	 * plat_get_my_stack() and plat_set_my_stack() are supported by the
 	 * platform and the previous APIs platform_get_stack() and
 	 * platform_set_stack() are defined in terms of new APIs making use of