drm/i915: use register name when disabling VGA

Just noticed this while verifying the VGA disable code.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -9522,7 +9522,7 @@ static void i915_disable_vga(struct drm_device *dev)
 		vga_reg = VGACNTRL;
 
 	vga_get_uninterruptible(dev->pdev, VGA_RSRC_LEGACY_IO);
-	outb(1, VGA_SR_INDEX);
+	outb(SR01, VGA_SR_INDEX);
 	sr1 = inb(VGA_SR_DATA);
 	outb(sr1 | 1<<5, VGA_SR_DATA);
 	vga_put(dev->pdev, VGA_RSRC_LEGACY_IO);