drm: move __OS_HAS_AGP into drm_agpsupport.h

With drm_memory.h gone, there is no header left that uses __OS_HAS_AGP.
Move it into drm_agpsupport.h (which is itself included from drmP.h) to
hide it harder from public eyes.
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

include/drm/drmP.h

@@ -67,8 +67,6 @@
 
 #include <linux/idr.h>
 
-#define __OS_HAS_AGP (defined(CONFIG_AGP) || (defined(CONFIG_AGP_MODULE) && defined(MODULE)))
-
 struct module;
 
 struct drm_file;

include/drm/drm_agpsupport.h

@@ -8,6 +8,9 @@
 #include <linux/agp_backend.h>
 #include <drm/drmP.h>
 
+#define __OS_HAS_AGP (defined(CONFIG_AGP) || (defined(CONFIG_AGP_MODULE) && \
+					      defined(MODULE)))
+
 struct drm_agp_head {
 	struct agp_kern_info agp_info;
 	struct list_head memory;