video: fbdev: arkfb: suppress build warning

this patch fixes following build warning:

drivers/video/fbdev/arkfb.c: In function ‘ark_pci_probe’:
drivers/video/fbdev/arkfb.c:1019:23: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
  par->state.vgabase = (void __iomem *) vga_res.start;
                       ^
Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/fbdev/arkfb.c

@@ -1016,7 +1016,7 @@ static int ark_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
 
 	pcibios_bus_to_resource(dev->bus, &vga_res, &bus_reg);
 
-	par->state.vgabase = (void __iomem *) vga_res.start;
+	par->state.vgabase = (void __iomem *) (unsigned long) vga_res.start;
 
 	/* FIXME get memsize */
 	regval = vga_rseq(par->state.vgabase, 0x10);