drm: add framebuffer maps

The patch makes drmAddBufs/drmMapBufs can handle buffers in video memory

The attached patch adds a new buffer type DRM_FB_BUFFER. It works like
AGP memory but uses video memory.

From: Austin Yuan <austinyuan@viatech.com.cn>
Signed-off-by: Dave Airlie <airlied@linux.ie>
diff --git a/drivers/char/drm/drmP.h b/drivers/char/drm/drmP.h
index 5df09cc..804e622 100644
--- a/drivers/char/drm/drmP.h
+++ b/drivers/char/drm/drmP.h
@@ -96,6 +96,7 @@
 #define DRIVER_IRQ_SHARED  0x80
 #define DRIVER_IRQ_VBL     0x100
 #define DRIVER_DMA_QUEUE   0x200
+#define DRIVER_FB_DMA      0x400
 
 /***********************************************************************/
 /** \name Begin the DRM... */
@@ -474,7 +475,8 @@
 	unsigned long	  byte_count;
 	enum {
 		_DRM_DMA_USE_AGP = 0x01,
-		_DRM_DMA_USE_SG  = 0x02
+		_DRM_DMA_USE_SG  = 0x02,
+		_DRM_DMA_USE_FB  = 0x04
 	} flags;
 
 } drm_device_dma_t;