Remove code for deleted function from ssl.h

ssl_cert_inst was removed in 2c3823491d8812560922a58677e3ad2db4b2ec8d

Reviewed-by: Dr. Stephen Henson <steve@openssl.org>

include/openssl/ssl.h

diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index 50a79a8..fae706b 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -2040,7 +2040,6 @@
 # define SSL_F_SSL_BYTES_TO_CIPHER_LIST                   161
 # define SSL_F_SSL_CERT_ADD0_CHAIN_CERT                   339
 # define SSL_F_SSL_CERT_DUP                               221
-# define SSL_F_SSL_CERT_INST                              222
 # define SSL_F_SSL_CERT_INSTANTIATE                       214
 # define SSL_F_SSL_CERT_NEW                               162
 # define SSL_F_SSL_CERT_SET0_CHAIN                        340