Revert "PCI: Add x86_msi.msi_mask_irq() and msix_mask_irq()"

The problem fixed by 0e4ccb1505a9 ("PCI: Add x86_msi.msi_mask_irq() and
msix_mask_irq()") has been fixed in a simpler way by a previous commit
("PCI/MSI: Add pci_msi_ignore_mask to prevent writes to MSI/MSI-X Mask
Bits").

The msi_mask_irq() and msix_mask_irq() x86_msi_ops added by 0e4ccb1505a9
are no longer needed, so revert the commit.

default_msi_mask_irq() and default_msix_mask_irq() were added by
0e4ccb1505a9 and are still used by s390, so keep them for now.

[bhelgaas: changelog]
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: xen-devel@lists.xenproject.org
diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 5ef62ed..466b978 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -394,14 +394,7 @@
 {
 	xen_destroy_irq(irq);
 }
-static u32 xen_nop_msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag)
-{
-	return 0;
-}
-static u32 xen_nop_msix_mask_irq(struct msi_desc *desc, u32 flag)
-{
-	return 0;
-}
+
 #endif
 
 int __init pci_xen_init(void)
@@ -425,8 +418,6 @@
 	x86_msi.setup_msi_irqs = xen_setup_msi_irqs;
 	x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
 	x86_msi.teardown_msi_irqs = xen_teardown_msi_irqs;
-	x86_msi.msi_mask_irq = xen_nop_msi_mask_irq;
-	x86_msi.msix_mask_irq = xen_nop_msix_mask_irq;
 	pci_msi_ignore_mask = 1;
 #endif
 	return 0;
@@ -507,8 +498,6 @@
 	x86_msi.setup_msi_irqs = xen_initdom_setup_msi_irqs;
 	x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
 	x86_msi.restore_msi_irqs = xen_initdom_restore_msi_irqs;
-	x86_msi.msi_mask_irq = xen_nop_msi_mask_irq;
-	x86_msi.msix_mask_irq = xen_nop_msix_mask_irq;
 	pci_msi_ignore_mask = 1;
 #endif
 	xen_setup_acpi_sci();