drm: Add general-purpose packet for manipulating scratch registers (r300)

From: Aapo Tahkola (via DRM CVS)
Signed-off-by: Dave Airlie <airlied@linux.ie>
diff --git a/drivers/char/drm/radeon_drm.h b/drivers/char/drm/radeon_drm.h
index bb63e68..c8e279e 100644
--- a/drivers/char/drm/radeon_drm.h
+++ b/drivers/char/drm/radeon_drm.h
@@ -222,6 +222,7 @@
 #	define R300_WAIT_3D  		0x2
 #	define R300_WAIT_2D_CLEAN  	0x3
 #	define R300_WAIT_3D_CLEAN  	0x4
+#define R300_CMD_SCRATCH		8
 
 typedef union {
 	unsigned int u;
@@ -247,6 +248,9 @@
 	struct {
 		unsigned char cmd_type, flags, pad0, pad1;
 	} wait;
+	struct {
+		unsigned char cmd_type, reg, n_bufs, flags;
+	} scratch;
 } drm_r300_cmd_header_t;
 
 #define RADEON_FRONT			0x1