ARM: DRA7: id: Add cpu detection support for DRA7xx based SoCs'

The DRA7xx is a high-performance, infotainment application device,
based on enhanced OMAP architecture integrated on a 28-nm technology.

Since DRA7 is a platform supported only using DT, the cpu detection
is based on the compatibles passed from DT blobs as suggested here
http://lists.infradead.org/pipermail/linux-arm-kernel/2013-July/187712.html

Suggested-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: R Sricharan <r.sricharan@ti.com>
Signed-off-by: Rajendra Nayak <rnayak@ti.com>