[CORE] Add dma_mask to vmm_device

This patch adds the dma_mask to device structure which will help
driver porting, as most of the devices have inbuild dma.

Signed-off-by: Ankit Jindal <thatsjindal@gmail.com>
[DRIVERS] Add linux/dma_mapping.h for driver porting

Signed-off-by: Ankit Jindal <thatsjindal@gmail.com>