Add a common helper for dma-mapping core for mapping a coherent buffer
to userspace.
Reported-by: NSubash Patel <subashrp@gmail.com>
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Acked-by: NKyungmin Park <kyungmin.park@samsung.com>
Tested-By: NSubash Patel <subash.ramaswamy@linaro.org>