PCI: remove PCI_DMA_BUS_IS_PHYS

This was used by the ide, scsi and networking code in the past to
determine if they should bounce payloads.  Now that the dma mapping
always have to support dma to all physical memory (thanks to swiotlb
for non-iommu systems) there is no need to this crude hack any more.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Palmer Dabbelt <palmer@sifive.com> (for riscv)
Reviewed-by: Jens Axboe <axboe@kernel.dk>

arch/m68k/include/asm/pci.h

@@ -4,12 +4,6 @@
 
 #include <asm-generic/pci.h>
 
-/* The PCI address space does equal the physical memory
- * address space.  The networking and block device layers use
- * this boolean for bounce buffer decisions.
- */
-#define PCI_DMA_BUS_IS_PHYS	(1)
-
 #define	pcibios_assign_all_busses()	1
 
 #define	PCIBIOS_MIN_IO		0x00000100