drm: move to kref per-master structures.

This is step one towards having multiple masters sharing a drm
device in order to get fast-user-switching to work.

It splits out the information associated with the drm master
into a separate kref counted structure, and allocates this when
a master opens the device node. It also allows the current master
to abdicate (say while VT switched), and a new master to take over
the hardware.

It moves the Intel and radeon drivers to using the sarea from
within the new master structures.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/i915/i915_mem.c b/drivers/gpu/drm/i915/i915_mem.c
index 6126a60..96e2719 100644
--- a/drivers/gpu/drm/i915/i915_mem.c
+++ b/drivers/gpu/drm/i915/i915_mem.c
@@ -46,7 +46,8 @@
 static void mark_block(struct drm_device * dev, struct mem_block *p, int in_use)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
-	drm_i915_sarea_t *sarea_priv = dev_priv->sarea_priv;
+	struct drm_i915_master_private *master_priv = dev->primary->master->driver_priv;
+	drm_i915_sarea_t *sarea_priv = master_priv->sarea_priv;
 	struct drm_tex_region *list;
 	unsigned shift, nr;
 	unsigned start;