mm: dma-mapping: sync iova prefetch gap code

mm: dma-mapping: sync iova prefetch gap code

Sync iova prefetch gap dma code between arm and arm64.

Change-Id: I830b401cba205f56b2e17d1623cd15777aa89b39
Signed-off-by: Krishna Reddy <vdumpa@nvidia.com>
Reviewed-on: http://git-master/r/345941
Tested-by: Xue Dong <xdong@nvidia.com>
Reviewed-by: Hiroshi Doyu <hdoyu@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-on: http://git-master/r/346664
Reviewed-by: Chao Xu <cxu@nvidia.com>
Tested-by: Chao Xu <cxu@nvidia.com>