Fix typos

Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 0dd762e..290c4c6 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -1270,7 +1270,7 @@
             ssl->session_negotiate->ciphersuite);
         ssl->handshake->ciphersuite_info = ciphersuite_info;
 
-        /* Enable psk and psk_ephermal to make stage early happy */
+        /* Enable psk and psk_ephemeral to make stage early happy */
         ssl->handshake->key_exchange_mode =
             MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ALL;