PCI/MSI: Rename mask/unmask_msi_irq et al

mask/unmask_msi_irq and __mask_msi/msix_irq are PCI/MSI specific
functions and should be named accordingly. This is a preparatory patch
to support MSI on non PCI devices.

Rename mask/unmask_msi_irq to pci_msi_mask/unmask_irq and document the
functions. Provide conversion helpers.

Rename __mask_msi/msix_irq to __pci_msi/msix_desc_mask so its clear
that they operated on msi_desc. Fixup the only user outside of
pci/msi.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Yijing Wang <wangyijing@huawei.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index ad1a9e2..fb54bbd 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -448,9 +448,9 @@
 	/* Release MSI interrupts */
 	list_for_each_entry(msi, &pdev->msi_list, list) {
 		if (msi->msi_attrib.is_msix)
-			__msix_mask_irq(msi, 1);
+			__pci_msix_desc_mask_irq(msi, 1);
 		else
-			__msi_mask_irq(msi, 1, 1);
+			__pci_msi_desc_mask_irq(msi, 1, 1);
 		irq_set_msi_desc(msi->irq, NULL);
 		irq_free_desc(msi->irq);
 		msi->msg.address_lo = 0;