memshare: Change dma attribute to DMA_ATTR_NO_KERNEL_MAPPING

Currently xpu violation is happening as the allocated piece of
memory is being accessed from the apps. Change the attribute to
DMA_ATTR_NO_KERNEL_MAPPING so that apps cannot access the
allocated piece of memory.

Change-Id: Icbda155c3d9ea28570e7d17240ee23f8f12061a9
CRs-Fixed: 825907
Signed-off-by: Katish Paran <kparan@codeaurora.org>