kgsl/drm/dts: Add drm dts file for kgsl-drm.

This patch adds drm dts file for kgsl-drm platform device.
currently kgsl initialization the kgsl-drm. but If we need to support
vsync irq feature in the kgsl-drm. we should seperate kgsl-drm from
kgsl.

Change-Id: I650e126352f02758db9505c38152228f2002fa18
Signed-off-by: Beeresh Gopal <gbeeresh@codeaurora.org>