MIPS: make PCI_DMA_BUS_IS_PHYS=1 constant

No one of supported MIPS machines has an IOMMU unit, so we can safely define
PCI_DMA_BUS_IS_PHYS = 1. Also remove iommu flag from the pci controller
structure, since it is useless.

Signed-off-by: Sergey Ryazanov <[e-mail]>
Cc: Linux MIPS <[e-mail]>
Patchwork: https://patchwork.linux-mips.org/patch/7604/
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/include/asm/pci.h

···
 	   and XFree86. Eventually will be removed. */
 	unsigned int need_domain_info;
 
-	int iommu;
-
 	/* Optional access methods for reading/writing the bus number
 	   of the PCI controller */
 	int (*get_busno)(void);
···
 struct pci_dev;
 
 /*
- * The PCI address space does equal the physical memory address space.	The
- * networking and block device layers use this boolean for bounce buffer
- * decisions.  This is set if any hose does not have an IOMMU.
+ * The PCI address space does equal the physical memory address space.
+ * The networking and block device layers use this boolean for bounce
+ * buffer decisions.
  */
-extern unsigned int PCI_DMA_BUS_IS_PHYS;
+#define PCI_DMA_BUS_IS_PHYS     (1)
 
 #ifdef CONFIG_PCI_DOMAINS
 #define pci_domain_nr(bus) ((struct pci_controller *)(bus)->sysdata)->index

arch/mips/kernel/setup.c

···
 #endif
 
 /*
- * Despite it's name this variable is even if we don't have PCI
- */
-unsigned int PCI_DMA_BUS_IS_PHYS;
-
-EXPORT_SYMBOL(PCI_DMA_BUS_IS_PHYS);
-
-/*
  * Setup information
  *
  * These are initialized so they are in the .data section

arch/mips/pci/pci-ip32.c

···
 	.pci_ops	= &mace_pci_ops,
 	.mem_resource	= &mace_pci_mem_resource,
 	.io_resource	= &mace_pci_io_resource,
-	.iommu		= 0,
 	.mem_offset	= MACE_PCI_MEM_OFFSET,
 	.io_offset	= 0,
 	.io_map_base	= CKSEG1ADDR(MACEPCI_LOW_IO),

arch/mips/pci/pci.c

···
 	LIST_HEAD(resources);
 	struct pci_bus *bus;
 
-	if (!hose->iommu)
-		PCI_DMA_BUS_IS_PHYS = 1;
-
 	if (hose->get_busno && pci_has_flag(PCI_PROBE_ONLY))
 		next_busno = (*hose->get_busno)();
 

arch/mips/pnx833x/common/setup.c

···
 
 int __init plat_mem_setup(void)
 {
-	/* fake pci bus to avoid bounce buffers */
-	PCI_DMA_BUS_IS_PHYS = 1;
-
 	/* set mips clock to 320MHz */
 #if defined(CONFIG_SOC_PNX8335)
 	PNX8335_WRITEFIELD(0x17, CLOCK_PLL_CPU_CTL, FREQ);