doc: Add missing parameter for msi_setup

commit 92ca8d20dee2 ("genirq/msi: Switch to new irq spreading")
introduced new parameter to msi_init_setup and but did not update
docbook comments. Fixes 'make htmldocs' warning.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Cc: bhelgaas@google.com
Cc: linux-pci@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

drivers/pci/msi.c

@@ -610,6 +610,7 @@ static int msi_verify_entries(struct pci_dev *dev)
  * msi_capability_init - configure device's MSI capability structure
  * @dev: pointer to the pci_dev data structure of MSI device function
  * @nvec: number of interrupts to allocate
+ * @affinity: flag to indicate cpu irq affinity mask should be set
  *
  * Setup the MSI capability structure of the device with the requested
  * number of interrupts.  A return value of zero indicates the successful
@@ -752,6 +753,7 @@ static void msix_program_entries(struct pci_dev *dev,
  * @dev: pointer to the pci_dev data structure of MSI-X device function
  * @entries: pointer to an array of struct msix_entry entries
  * @nvec: number of @entries
+ * @affinity: flag to indicate cpu irq affinity mask should be set
  *
  * Setup the MSI-X capability structure of device function with a
  * single MSI-X irq. A return of zero indicates the successful setup of