[ARM] pxafb: allow video memory size to be configurable

The amount of video memory size is decided according to the following
order:

1. <xres> x <yres> x <bits_per_pixel> by default, which is the backward
   compatible way

2. size specified in platform data

3. size specified in module parameter 'options' string or specified in
   kernel boot command line (see updated Documentation/fb/pxafb.txt)

And now since the memory is allocated from system memory, the pxafb_mmap
can be removed and the default fb_mmap() should be working all right.

Also, since we now have introduced the 'struct pxafb_dma_buff' for DMA
descriptors and palettes, the allocation can be separated cleanly.

NOTE: the LCD DMA actually supports chained transfer (i.e. page-based
transfers), to simplify the logic and keep the performance (with less
TLB misses when accessing from memory mapped user space), the memory
is allocated by alloc_pages_*() to ensures it's physical contiguous.

Signed-off-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Eric Miao <ycmiao@ycmiao-hp520.(none)>
diff --git a/drivers/video/pxafb.h b/drivers/video/pxafb.h
index d8eb93f..0981938 100644
--- a/drivers/video/pxafb.h
+++ b/drivers/video/pxafb.h
@@ -69,24 +69,15 @@
 	void __iomem		*mmio_base;
 
 	struct pxafb_dma_buff	*dma_buff;
+	size_t			dma_buff_size;
 	dma_addr_t		dma_buff_phys;
 	dma_addr_t		fdadr[DMA_MAX];
 
-	/*
-	 * These are the addresses we mapped
-	 * the framebuffer memory region to.
-	 */
-	/* raw memory addresses */
-	dma_addr_t		map_dma;	/* physical */
-	u_char *		map_cpu;	/* virtual */
-	u_int			map_size;
-
-	/* addresses of pieces placed in raw buffer */
-	u_char *		screen_cpu;	/* virtual address of frame buffer */
-	dma_addr_t		screen_dma;	/* physical address of frame buffer */
+	void __iomem		*video_mem;	/* virtual address of frame buffer */
+	unsigned long		video_mem_phys;	/* physical address of frame buffer */
+	size_t			video_mem_size;	/* size of the frame buffer */
 	u16 *			palette_cpu;	/* virtual address of palette memory */
 	u_int			palette_size;
-	ssize_t			video_offset;
 
 	u_int			lccr0;
 	u_int			lccr3;