drm/radeon: include radeon_asic.h in the asic specific files

In essence this creates a home for all asic specific declarations in
radeon_asic.h

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r420.c b/drivers/gpu/drm/radeon/r420.c
index c7593b8..2ab35ff 100644
--- a/drivers/gpu/drm/radeon/r420.c
+++ b/drivers/gpu/drm/radeon/r420.c
@@ -29,6 +29,7 @@
 #include "drmP.h"
 #include "radeon_reg.h"
 #include "radeon.h"
+#include "radeon_asic.h"
 #include "atom.h"
 #include "r100d.h"
 #include "r420d.h"