ssh/channel-type.c (_ssh_channel_to_scm): Rename

* ssh/channel-type.c (_ssh_channel_to_scm): Rename to
  `_scm_from_channel_data'.  All callers updated.
  (guile_ssh_make_channel): Update.
* ssh/channel-type.h: Update.
* ssh/message-func.c
  (guile_ssh_message_channel_request_open_reply_accept): Update.