libdrm: Add DRM_IOCTL_TEGRA_(START|STOP)_KEEPON ioctls

Add struct drm_tegra_keepon, and corresponding ioctl opcodes.  These are
pulled from chromeos-3.18 kernel.

Change-Id: I74d2c82cce7888ce1781e19292b6eacb87325be1
Signed-off-by: Andrew Chew <achew@nvidia.com>
1 file changed