Fix typos in C header files

Signed-off-by: Tobias Nießen <tniessen@tnie.de>
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 7815ad9..4684a60 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -4327,7 +4327,7 @@
 /**
  * \brief          TLS-PRF function for key derivation.
  *
- * \param prf      The tls_prf type funtion type to be used.
+ * \param prf      The tls_prf type function type to be used.
  * \param secret   Secret for the key derivation function.
  * \param slen     Length of the secret.
  * \param label    String label for the key derivation function,
@@ -4337,7 +4337,7 @@
  * \param dstbuf   The buffer holding the derived key.
  * \param dlen     Length of the output buffer.
  *
- * \return         0 on sucess. An SSL specific error on failure.
+ * \return         0 on success. An SSL specific error on failure.
  */
 int  mbedtls_ssl_tls_prf( const mbedtls_tls_prf_types prf,
                           const unsigned char *secret, size_t slen,