swiotlb: change swiotlb_bus_to[phys,virt] prototypes

Add a hwdev argument that is needed on some architectures
in order to access a per-device offset that is taken into
account when producing a physical address (also needed to
get from bus address to virtual address because the physical
address is an intermediate step).

Also make swiotlb_bus_to_virt weak so architectures can
override it.

Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Cc: jeremy@goop.org
Cc: ian.campbell@citrix.com
LKML-Reference: <1239199761-22886-8-git-send-email-galak@kernel.crashing.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
index 34f12e9..887388a 100644
--- a/arch/x86/kernel/pci-swiotlb.c
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -28,7 +28,7 @@
 	return paddr;
 }
 
-phys_addr_t swiotlb_bus_to_phys(dma_addr_t baddr)
+phys_addr_t swiotlb_bus_to_phys(struct device *hwdev, dma_addr_t baddr)
 {
 	return baddr;
 }