CLEANUP: ssl: make load_srv_{ckchs,cert} match their bind counterpart

CLEANUP: ssl: make load_srv_{ckchs,cert} match their bind counterpart

This patch makes things more consistent between the bind_conf functions
and the server ones:

- ssl_sock_load_srv_ckchs() loads the SSL_CTX in the server
  (ssl_sock_load_ckchs() load the SNIs in the bind_conf)

- add the server parameter to ssl_sock_load_srv_ckchs()

- changes made to the ckch_inst are done in
  ckch_inst_new_load_srv_store()