Use proper abstractions in quirk_intel_irqbalance

Since we may not have a pci_dev for the device we need to access, we can't
use pci_read_config_word.  But raw_pci_read is an internal implementation
detail; it's better to use the architected pci_bus_read_config_word
interface.  Using PCI_DEVFN instead of a mysterious constant helps
reassure everyone that we really do intend to access device 8.

[ Thanks to Grant Grundler for pointing out to me that this is exactly
  what the write immediately above this is doing -- enabling device 8 to
  respond to config space cycles.
					- Matthew

  Grant also says:

	"Can you also add a comment which points at the Intel
	 documentation?

	 The 'Intel E7320 Memory Controller Hub (MCH) Datasheet' at

	  http://download.intel.com/design/chipsets/datashts/30300702.pdf

	 Page 69 documents register F4h (DEVPRES1).

	 And I just doubled checked that the 0xf4 register value is
	 restored later in the quirk (obvious when you look at the code
	 but not from the patch"

  so here it is.
					 - Linus ]
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Acked-by: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/kernel/quirks.c

@@ -11,7 +11,7 @@
 static void __devinit quirk_intel_irqbalance(struct pci_dev *dev)
 {
 	u8 config, rev;
-	u32 word;
+	u16 word;
 
 	/* BIOS may enable hardware IRQ balancing for
 	 * E7520/E7320/E7525(revision ID 0x9 and below)
@@ -26,8 +26,11 @@ static void __devinit quirk_intel_irqbalance(struct pci_dev *dev)
 	pci_read_config_byte(dev, 0xf4, &config);
 	pci_write_config_byte(dev, 0xf4, config|0x2);
 
-	/* read xTPR register */
-	raw_pci_read(0, 0, 0x40, 0x4c, 2, &word);
+	/*
+	 * read xTPR register.  We may not have a pci_dev for device 8
+	 * because it might be hidden until the above write.
+	 */
+	pci_bus_read_config_word(dev->bus, PCI_DEVFN(8, 0), 0x4c, &word);
 
 	if (!(word & (1 << 13))) {
 		dev_info(&dev->dev, "Intel E7520/7320/7525 detected; "