drm/vmwgfx: Add surface dirty-tracking callbacks

Add the callbacks necessary to implement emulated coherent memory for
surfaces. Add a flag to the gb_surface_create ioctl to indicate that
surface memory should be coherent.
Also bump the drm minor version to signal the availability of coherent
surfaces.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Deepak Rawat <drawat@vmware.com>

include/uapi/drm/vmwgfx_drm.h

@@ -891,11 +891,13 @@ struct drm_vmw_shader_arg {
  *                                      surface.
  * @drm_vmw_surface_flag_create_buffer: Create a backup buffer if none is
  *                                      given.
+ * @drm_vmw_surface_flag_coherent:      Back surface with coherent memory.
  */
 enum drm_vmw_surface_flags {
 	drm_vmw_surface_flag_shareable = (1 << 0),
 	drm_vmw_surface_flag_scanout = (1 << 1),
-	drm_vmw_surface_flag_create_buffer = (1 << 2)
+	drm_vmw_surface_flag_create_buffer = (1 << 2),
+	drm_vmw_surface_flag_coherent = (1 << 3),
 };
 
 /**