drm/tegra: Changes for v3.15-rc1

Implement eDP support for Tegra124 and support the PRIME vmap()/vunmap()
operations.

A symbol that is required for upcoming V4L2 support is now exported by
the host1x driver.

Relicense drivers under the GPL v2 for consistency. One exception is the
public header file, which is relicensed under MIT to abide by the common
rule.

* tag 'drm/tegra/for-3.15-rc1' of git://anongit.freedesktop.org/tegra/linux:
  drm/tegra: Use standard GPL v2 license text
  drm/tegra: Relicense under GPL v2
  drm/tegra: Relicense public header under MIT
  drm/tegra: Add eDP support
  gpu: host1x: export host1x_syncpt_incr_max() function
  drm/tegra: prime: Add vmap support