virt: acrn: Remove unused list 'acrn_irqfd_clients'

It doesn't look like this was ever used.

Build tested only.

Signed-off-by: "Dr. David Alan Gilbert" <linux@treblig.org>
Acked-by: Fei Li <fei1.li@intel.com>
Link: https://lore.kernel.org/r/20250430003623.313541-1-linux@treblig.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Dr. David Alan Gilbert

drivers/virt/acrn/irqfd.c

@@ -16,8 +16,6 @@
 
 #include "acrn_drv.h"
 
-static LIST_HEAD(acrn_irqfd_clients);
-
 /**
  * struct hsm_irqfd - Properties of HSM irqfd
  * @vm:		Associated VM pointer