vfio scsi ui: Error-check qio_channel_socket_connect_sync() the same way

qio_channel_socket_connect_sync() returns 0 on success, and -1 on
failure, with errp set.  Some callers check the return value, and some
check whether errp was set.

For consistency, always check the return value, and always check it's
negative.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20250723133257.1497640-3-armbru@redhat.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
3 files changed