Export drm APIs to support early camera.

Export drm APIs to support early camera.

To mmap camera videos to the spriteC plane(Intel i915), early camera
will bypass DRM_IOCTL to avoid drm_master conflicting issues, and
call drm APIs directly. Because drm APIs are for user space
framworks and applications, it is necessary to export them for
early camera module.
For the details of early camera, please check the wiki page:
https://wiki.tizen.org/wiki/Early_Camera

Change-Id: I26773dd5aa50f68011c92350f8af3ba88aade426
Signed-off-by: Fang, Neo <neo.fang@intel.com>