PCI: Replace HAVE_ARCH_PCI_MWI with PCI_DISABLE_MWI

pSeries is the only architecture left using HAVE_ARCH_PCI_MWI and it's
really inappropriate for its needs.  It really wants to disable MWI
altogether.  So here are a pair of stub implementations for pci_set_mwi
and pci_clear_mwi.

Also rename pci_generic_prep_mwi to pci_set_cacheline_size since that
better reflects what it does.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/asm-powerpc/pci.h b/include/asm-powerpc/pci.h
index 46afd29..721c97f0 100644
--- a/include/asm-powerpc/pci.h
+++ b/include/asm-powerpc/pci.h
@@ -62,19 +62,13 @@
 }
 
 #ifdef CONFIG_PPC64
-#define HAVE_ARCH_PCI_MWI 1
-static inline int pcibios_prep_mwi(struct pci_dev *dev)
-{
-	/*
-	 * We would like to avoid touching the cacheline size or MWI bit
-	 * but we cant do that with the current pcibios_prep_mwi 
-	 * interface. pSeries firmware sets the cacheline size (which is not
-	 * the cpu cacheline size in all cases) and hardware treats MWI 
-	 * the same as memory write. So we dont touch the cacheline size
-	 * here and allow the generic code to set the MWI bit.
-	 */
-	return 0;
-}
+
+/*
+ * We want to avoid touching the cacheline size or MWI bit.
+ * pSeries firmware sets the cacheline size (which is not the cpu cacheline
+ * size in all cases) and hardware treats MWI the same as memory write.
+ */
+#define PCI_DISABLE_MWI
 
 extern struct dma_mapping_ops pci_dma_ops;