drm/amdgpu: Port to DragonFly

drm/amdgpu: Port to DragonFly

* This commit does not build as it requires ttm changes from
  the corresponding commit

Amdgpu driver changes:
* Builds with CONFIG_DRM_AMD_DC and CONFIG_DRM_AMD_DC_DCN1_0 defined
* Support for older GPUs (SI, CIK) is not implemented
* Several functions for display core module require msse and
  mhard-float gcc flags to be set; and they require special
  treatment from kernel by utilizing kernel_fpu_begin/kernel_fpu_end
  functions
* It is required that tunable set amdgpu_hw_i2c=1 to work around
  panic during module load
* Thunderbolt support is disabled
* Amdgpu trace infrastructure replaced by a stub

Drm changes:
* register_framebuffer is called at the later stage, after crtcs
  were properly initialized
* drm_close implemented
* drm_connector_update_edid_property implemented
* Fix drm device stays locked in case of an error or module shutdown
* Imported drm gem framebuffer helper functions
* Fixed null pointer deref in the drm mmap ioctl
* Imported atomic64_inc and atomic_long_* functions from Linux
* Imported bitmap_complement function from Linux
* Imported kfifo struct from Linux
* Implemented dma fence array properly
* Imported rb_root_cached struct from Linux
* Implemented several dma fence functions

Co-authored-by: François Tigeot <ftigeot@wolfpond.org>
Co-authored-by: Matthew Dillon <dillon@apollo.backplane.com>