drm/radeon: initial VCE support v4

Only VCE 2.0 support so far.

v2: squashing multiple patches into this one
v3: add IRQ support for CIK, major cleanups,
    basic code documentation
v4: remove HAINAN from chipset list

Signed-off-by: Christian König <christian.koenig@amd.com>
15 files changed