misc: ocxl: fix possible refcount leak in afu_ioctl()

eventfd_ctx_put need to be called to put the refcount that gotten by
eventfd_ctx_fdget when ocxl_irq_set_handler fails.

Fixes: 0601466146 ("ocxl: move event_fd handling to frontend")
Acked-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Link: https://lore.kernel.org/r/20220824082600.36159-1-hbh25y@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/ocxl/file.c

@@ -257,6 +257,8 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 		if (IS_ERR(ev_ctx))
 			return PTR_ERR(ev_ctx);
 		rc = ocxl_irq_set_handler(ctx, irq_id, irq_handler, irq_free, ev_ctx);
+		if (rc)
+			eventfd_ctx_put(ev_ctx);
 		break;
 
 	case OCXL_IOCTL_GET_METADATA: