Initial BLTsville API definition.

BLTsville is the open 2-D API designed to provide an abstract
interface for both hardware and software 2-D implementations.

BLTs (BLock Transfers) involve the moving around of blocks
(rectangles) of pixels.

Change-Id: I871f2821d8ec257899c7ac3b26a16ab219f48920
Signed-off-by: Rick Tillery <rtillery@ti.com>
Signed-off-by: David Sin <davidsin@ti.com>