cxl/pci: Update comment

The existence of struct cxl_dev_id containing a single member is odd.
The comment made sense when I wrote it but could be clarified.

Update the comment and place it next to the odd looking structure.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20230426-cxl-fixes-v1-2-870c4c8b463a@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Author: weiny2

drivers/cxl/pci.c

@@ -85,6 +85,10 @@ static int cxl_pci_mbox_wait_for_doorbell(struct cxl_dev_state *cxlds)
 			    status & CXLMDEV_DEV_FATAL ? " fatal" : "",        \
 			    status & CXLMDEV_FW_HALT ? " firmware-halt" : "")
 
+/*
+ * Threaded irq dev_id's must be globally unique.  cxl_dev_id provides a unique
+ * wrapper object for each irq within the same cxlds.
+ */
 struct cxl_dev_id {
 	struct cxl_dev_state *cxlds;
 };
@@ -95,7 +99,6 @@ static int cxl_request_irq(struct cxl_dev_state *cxlds, int irq,
 	struct device *dev = cxlds->dev;
 	struct cxl_dev_id *dev_id;
 
-	/* dev_id must be globally unique and must contain the cxlds */
 	dev_id = devm_kzalloc(dev, sizeof(*dev_id), GFP_KERNEL);
 	if (!dev_id)
 		return -ENOMEM;