components/openssl: optimize the SSL certification and private key function

1. add inheritance function
2. remove low-level platform unload cert & pkey function
3. optimize the cert load and free function

components/openssl/include/internal/ssl_pkey.h

@@ -21,6 +21,15 @@
 
 #include "ssl_types.h"
 
+/**
+ * @brief create a private key object according to input private key
+ *
+ * @param ipk - input private key point
+ *
+ * @return new private key object point
+ */
+EVP_PKEY* __EVP_PKEY_new(EVP_PKEY *ipk);
+
 /**
  * @brief create a private key object
  *