drm/vmwgfx: Replace iowrite/ioread with volatile memory accesses

Now that we use memremap instead of ioremap, Use WRITE_ONCE / READ_ONCE
instead of iowrite / ioread.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
index bee0a45..d1c34ab 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -752,14 +752,8 @@
 	ttm_lock_set_kill(&dev_priv->fbdev_master.lock, false, SIGTERM);
 	dev_priv->active_master = &dev_priv->fbdev_master;
 
-	/*
-	 * Force __iomem for this mapping until the implied compiler
-	 * barriers and {READ|WRITE}_ONCE semantics from the
-	 * io{read|write}32() accessors can be replaced with explicit
-	 * barriers.
-	 */
-	dev_priv->mmio_virt = (void __iomem *) memremap(dev_priv->mmio_start,
-					    dev_priv->mmio_size, MEMREMAP_WB);
+	dev_priv->mmio_virt = memremap(dev_priv->mmio_start,
+				       dev_priv->mmio_size, MEMREMAP_WB);
 
 	if (unlikely(dev_priv->mmio_virt == NULL)) {
 		ret = -ENOMEM;
@@ -913,7 +907,7 @@
 out_no_device:
 	ttm_object_device_release(&dev_priv->tdev);
 out_err4:
-	memunmap((void __force *) dev_priv->mmio_virt);
+	memunmap(dev_priv->mmio_virt);
 out_err3:
 	vmw_ttm_global_release(dev_priv);
 out_err0:
@@ -964,7 +958,7 @@
 		pci_release_regions(dev->pdev);
 
 	ttm_object_device_release(&dev_priv->tdev);
-	memunmap((void __force *) dev_priv->mmio_virt);
+	memunmap(dev_priv->mmio_virt);
 	if (dev_priv->ctx.staged_bindings)
 		vmw_binding_state_free(dev_priv->ctx.staged_bindings);
 	vmw_ttm_global_release(dev_priv);