This patch adds the driver for the general purpose DMA hardware
block on newer Tegra SoCs. The GPCDMA is a special purpose DMA
used to speed up memory copy operations to/from DRAM and TZSRAM.

This patch introduces a macro 'USE_GPC_DMA' to allow platforms
to override CPU based memory operations.

Change-Id: I3170d409c83b77e785437b1002a8d70188fabbeb
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>