make drm headers use strict integer types

The drm headers are traditionally shared with BSD and
could not use the strict linux integer types. This is
over now, so we can use our own types now.

Cc: David Airlie <airlied@linux.ie>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>