virsh: Require option name for '--pass-fd' argument of 'qemu-monitor-command'

Require the option name for this argument as otherwise a part of the
'cmd' argument will be claimed.

Fixes: 43edde82af
Signed-off-by: Peter Krempa <pkrempa@redhat.com>

tools/virsh-domain.c

@@ -9723,6 +9723,7 @@ static const vshCmdOptDef opts_qemu_monitor_command[] = {
     },
     {.name = "pass-fds",
      .type = VSH_OT_STRING,
+     .flags = VSH_OFLAG_REQ_OPT,
      .completer = virshCompleteEmpty,
      .help = N_("pass file descriptors N,M,... along with the command")
     },