dma-mapping: Exclude remap functions when arch does not use DMA

The commit 'a106f65b("dma-mapping: Add dma_remap functions")' is
defined remap functions for ARM arch only, so it will break other
architecture compilation.

So remap functions are excluded, if arch is not using DMA.

Change-Id: Id39fcbac74f30a0ab1b3ce0c780460017ea189e5
Signed-off-by: Naveen Ramaraj <nramaraj@codeaurora.org>
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>