drm/amd: drop use of drmP.h in amdgpu/amdgpu*

Drop use of drmP.h in all files named amdgpu*
in drm/amd/amdgpu/

Fix fallout.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: "David (ChunMing) Zhou" <David1.Zhou@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190609220757.10862-10-sam@ravnborg.org