drm/i915/dsb: s/dsb/dsb_color_vblank/

We'll soon utilize several DSBs during the commit. To that end
rename the current crtc_state->dsb to crtc_state->dsb_color_vblank
to better reflect its role (color managemnent stuff programmed during
vblank).

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240624191032.27333-14-ville.syrjala@linux.intel.com


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