of/platform: Re-add of_dma_configure()

Change d3aa0ced deleted of_dma_configure()
resulting in the dma mask being unset. This causes dma_alloc_coherent() to
fail on arm platforms.

Change-Id: Id03ae0410c7320415404de1cd7d444abb9266c56
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>