Fixes the following sparse warnings:
 drivers/char/drm/via_dmablit.c:111:35: warning: Using plain integer as NULL pointer
 drivers/char/drm/via_dmablit.c:584:23: warning: Using plain integer as NULL pointer
Signed-off-by: Luiz Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Dave Airlie <airlied@linux.ie>
        int num_desc = 0;
        int cur_line;
        dma_addr_t next = 0 | VIA_DMA_DPR_EC;
-       drm_via_descriptor_t *desc_ptr = 0;
+       drm_via_descriptor_t *desc_ptr = NULL;
 
        if (mode == 1) 
                desc_ptr = vsg->desc_pages[cur_descriptor_page];
        int ret = 0;
        
        vsg->direction = (draw) ? DMA_TO_DEVICE : DMA_FROM_DEVICE;
-       vsg->bounce_buffer = 0;
+       vsg->bounce_buffer = NULL;
 
        vsg->state = dr_via_sg_init;