drm/i915: Fix hibernate save/restore of VGA attribute regs

In hibernate, we may end up calling the VGA save regs function twice, so we need to make sure it's idempotent.  That means leaving ARX in index mode after the first save operation.  Fixes hibernate on 965.
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/char/drm/i915_drv.c

@@ -160,6 +160,7 @@ static void i915_save_vga(struct drm_device *dev)
 		dev_priv->saveAR[i] = i915_read_ar(st01, i, 0);
 	inb(st01);
 	outb(dev_priv->saveAR_INDEX, VGA_AR_INDEX);
+	inb(st01);
 
 	/* Graphics controller registers */
 	for (i = 0; i < 9; i++)
@@ -225,6 +226,7 @@ static void i915_restore_vga(struct drm_device *dev)
 		i915_write_ar(st01, i, dev_priv->saveAR[i], 0);
 	inb(st01); /* switch back to index mode */
 	outb(dev_priv->saveAR_INDEX | 0x20, VGA_AR_INDEX);
+	inb(st01);
 
 	/* VGA color palette registers */
 	outb(dev_priv->saveDACMASK, VGA_DACMASK);