fbdev: fix integer as NULL pointer warning

drivers/video/aty/atyfb_base.c:3359:26: warning: Using plain integer as NULL pointer
drivers/video/aty/radeon_base.c:2280:32: warning: Using plain integer as NULL pointer
drivers/video/matrox/matroxfb_base.h:203:25: warning: Using plain integer as NULL pointer
drivers/video/matrox/matroxfb_base.h:203:25: warning: Using plain integer as NULL pointer
drivers/video/sis/sis_main.c:5790:44: warning: Using plain integer as NULL pointer

Signed-off-by: Harvey Harrison <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/video/aty/atyfb_base.c

···
 
 	info->fix.mmio_start = raddr;
 	par->ati_regbase = ioremap(info->fix.mmio_start, 0x1000);
-	if (par->ati_regbase == 0)
+	if (par->ati_regbase == NULL)
 		return -ENOMEM;
 
 	info->fix.mmio_start += par->aux_start ? 0x400 : 0xc00;

drivers/video/aty/radeon_base.c

···
 	do {
 		rinfo->fb_base = ioremap (rinfo->fb_base_phys,
 					  rinfo->mapped_vram);
-	} while (   rinfo->fb_base == 0 &&
-		  ((rinfo->mapped_vram /=2) >= MIN_MAPPED_VRAM) );
+	} while (rinfo->fb_base == NULL &&
+		 ((rinfo->mapped_vram /= 2) >= MIN_MAPPED_VRAM));
 
 	if (rinfo->fb_base == NULL) {
 		printk (KERN_ERR "radeonfb (%s): cannot map FB\n",

drivers/video/matrox/matroxfb_base.h

···
 		virt->vaddr = ioremap_nocache(phys, size);
 	else
 		virt->vaddr = ioremap(phys, size);
-	return (virt->vaddr == 0); /* 0, !0... 0, error_code in future */
+	return (virt->vaddr == NULL); /* 0, !0... 0, error_code in future */
 }
 
 static inline void mga_iounmap(vaddr_t va) {

drivers/video/sis/sis_main.c

···
 	} else {
 		struct sis_video_info *countvideo = card_list;
 		ivideo->cardnumber = 1;
-		while((countvideo = countvideo->next) != 0)
+		while((countvideo = countvideo->next) != NULL)
 			ivideo->cardnumber++;
 	}