drm/vmwgfx: Get maximum mob size from register SVGA_REG_MOB_MAX_SIZE

This patch queries the register SVGA_REG_MOB_MAX_SIZE for the
maximum size of a single mob.

Signed-off-by: Charmaine Lee <charmainel@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
diff --git a/include/uapi/drm/vmwgfx_drm.h b/include/uapi/drm/vmwgfx_drm.h
index 9971c56..87792a5 100644
--- a/include/uapi/drm/vmwgfx_drm.h
+++ b/include/uapi/drm/vmwgfx_drm.h
@@ -87,6 +87,7 @@
 #define DRM_VMW_PARAM_MAX_SURF_MEMORY  7
 #define DRM_VMW_PARAM_3D_CAPS_SIZE     8
 #define DRM_VMW_PARAM_MAX_MOB_MEMORY   9
+#define DRM_VMW_PARAM_MAX_MOB_SIZE     10
 
 /**
  * struct drm_vmw_getparam_arg