Reduce the instruction overhead of OpenSSL calls

Hi，

From the openssl documentation, when the value of ret is greater than 0, the SSL_get_error() function returns SSL_ERROR_NONE. 

So, it seems that when the return value of SSL_read() or SSL_write() function is greater than 0, we don't need to make an error judgment. 

The attached patch attempts to reduce unnecessary error judgments. 

I am glad for feedback and reviews!