MFC (cherry pick)r306197,r306327,r306328,r308390,r308391,r310600,r314703:

cherry pick from r306197:
Nvidia Tegra 124 and Jetson TK1 related DTS.
r306327:
Update AHCI driver to match new dts tree
r306328:
Update PCI driver to match new dts tree
r308390:
Rework NVIDIA Tegra124 XUSBPAD driver.
- Adapt it for new, incompatible, DT bindings introduced by r306197. -
Add support for USB super speed pads/ports.
r308391:
Add NVIDIA Tegra XHCI driver and coresponding firmware blob.
r310600:
Implement drivers for NVIDIA tegra124 display controller, HDMI source and
host1x module. Unfortunately, tegra124 SoC doesn't have 2D acceleration
engine and 3D requires not yet started nouveau driver.
r314703:
Add support for card detect and write protect gpio pins to Tegra SDHCI.

Implement drivers for NVIDIA tegra124 display controller, HDMI source
and host1x module. Unfortunately, tegra124 SoC doesn't have 2D acceleration
engine and 3D requires not yet started nouveau driver.

These drivers forms a first non-x86 DRM2 enabled graphic stack.

Note, there are 2 outstanding issues:
- The code uses gross hack in order to be comply with
OBJT_MGTDEVICE pager. (See tegra_bo_init_pager() in tegra_bo.c)
- Due to improper(probably) refcounting in drm_gem_mmap_single()
(in drm_gem.c), the gem objects are never released.
I hope that I will be able to address both issues in finite time,
but I don't want to touch x86 world now.

MFC after: 1 month