drm/radeon: drop dependency on drm_os_linux.h

The drm_os_linux.h header file is deprecated.
Drop all uses of symbols from this file.
All macros are just opencoded.
A few adjustments to include files was required as the obsolete
drm_os_linux.h included these headers.

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/20190608080241.4958-4-sam@ravnborg.org