Redo of PR#5345. Fixed spelling and typographical errors found by CodeSpell.

Signed-off-by: Shaun Case <warmsocks@gmail.com>
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/ssl_tls12_client.c b/library/ssl_tls12_client.c
index 095db8f..f516efa 100644
--- a/library/ssl_tls12_client.c
+++ b/library/ssl_tls12_client.c
@@ -2276,7 +2276,7 @@
                 MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
             return( MBEDTLS_ERR_SSL_DECODE_ERROR );
         }
-    } /* FALLTROUGH */
+    } /* FALLTHROUGH */
 #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
 
 #if defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED) ||                       \