PCI: Remove unused PCI_MSIX_FLAGS_BIRMASK definition

PCI_MSIX_FLAGS_BIRMASK has been replaced by PCI_MSIX_TABLE_BIR for better
readability.  Now no one uses it, remove it.  No functional change.
Signed-off-by: NYijing Wang <wangyijing@huawei.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

include/uapi/linux/pci_regs.h

@@ -319,7 +319,6 @@
 #define PCI_MSIX_PBA		8	/* Pending Bit Array offset */
 #define  PCI_MSIX_PBA_BIR	0x00000007 /* BAR index */
 #define  PCI_MSIX_PBA_OFFSET	0xfffffff8 /* Offset into specified BAR */
-#define  PCI_MSIX_FLAGS_BIRMASK	(7 << 0)   /* deprecated */
 #define PCI_CAP_MSIX_SIZEOF	12	/* size of MSIX registers */
 
 /* MSI-X entry's format */