drm: kill more unused DRM macros

There are a few more macros in drmP.h that are unused; DRM_GET_PRIV_SAREA,
DRM_ARRAY_SIZE, and DRM_WAITCOUNT can go away completely.

Unfortunately, DRM_COPY is still used in one place, but we can at least
move it to where it's used.  It's an awful looking macro..

[akpm: fix overeagerness]
Signed-off-by: Andres Salomon <dilinger@collabora.co.uk>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>