arm: dma-mapping: Add dma_remap functions

After getting an allocation from dma_alloc_coherent, there
may be cases where it is necessary to remap the handle
into the CPU's address space (e.g. no CPU side mapping was
requested at allocation time but now one is needed). Add
APIs to bring a handle into the CPU address space again.

Change-Id: Ia954c603743ea5f6fbe24e79e4f0c00b94532675
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Ian Maund <imaund@codeaurora.org>
Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org>