video: fbdev: vt8623fb: suppress build warning

this patch fixes following build warning:
drivers/video/fbdev/vt8623fb.c: In function ‘vt8623_pci_probe’:
drivers/video/fbdev/vt8623fb.c:734:23: 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>