Remove invalid comment from mbedtls_cipher_set_padding_mode()

Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
diff --git a/include/mbedtls/cipher.h b/include/mbedtls/cipher.h
index 53ef2ad..9c8701d 100644
--- a/include/mbedtls/cipher.h
+++ b/include/mbedtls/cipher.h
@@ -852,7 +852,6 @@
  * \brief               This function sets the padding mode, for cipher modes
  *                      that use padding.
  *
- *                      The default passing mode is PKCS7 padding.
  *
  * \param ctx           The generic cipher context. This must be initialized and
  *                      bound to a cipher information structure.