drm/i915/dsb: Introduce intel_dsb_chain()

In order to handle the DEwake tricks without involving
the CPU we need a mechanism by which one DSB can start
another one. Add a basic function to do so. We'll extend
it later with additional code to actually deal with
DEwake.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240624191032.27333-11-ville.syrjala@linux.intel.com


Reviewed-by: Animesh Manna <animesh.manna@intel.com>