error: Use error_reportf_err() where appropriate

Replace

    error_report("...: %s", ..., error_get_pretty(err));

by

    error_reportf_err(err, "...: ", ...);

One of the replaced messages lacked a colon.  Add it.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200505101908.6207-6-armbru@redhat.com>
diff --git a/scsi/qemu-pr-helper.c b/scsi/qemu-pr-helper.c
index 181ed4a..57ad830 100644
--- a/scsi/qemu-pr-helper.c
+++ b/scsi/qemu-pr-helper.c
@@ -1030,8 +1030,8 @@
         server_ioc = qio_channel_socket_new_fd(FIRST_SOCKET_ACTIVATION_FD,
                                                &local_err);
         if (server_ioc == NULL) {
-            error_report("Failed to use socket activation: %s",
-                         error_get_pretty(local_err));
+            error_reportf_err(local_err,
+                              "Failed to use socket activation: ");
             exit(EXIT_FAILURE);
         }
     }