x86: Kill bad_dma_address variable

This kills bad_dma_address variable, the old mechanism to enable
IOMMU drivers to make dma_mapping_error() work in IOMMU's
specific way.

bad_dma_address variable was introduced to enable IOMMU drivers
to make dma_mapping_error() work in IOMMU's specific way.
However, it can't handle systems that use both swiotlb and HW
IOMMU. SO we introduced dma_map_ops->mapping_error to solve that
case.

Intel VT-d, GART, and swiotlb already use
dma_map_ops->mapping_error. Calgary, AMD IOMMU, and nommu use
zero for an error dma address. This adds DMA_ERROR_CODE and
converts them to use it (as SPARC and POWER does).

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: muli@il.ibm.com
Cc: joerg.roedel@amd.com
LKML-Reference: <1258287594-8777-3-git-send-email-fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>