drm: msm: sde: Clear SB DMA flag upon sending SB DMA last command

Previous SB DMA logic was not clearing a "SB DMA active" flag, resulting
in SB DMA incorrectly being flushed every frame. While this logic
matches the DB DMA approach, it is unnecessary and could result in
delayed DB DMA execution.

Update SB DMA logic to clear the "active" flag for the target DSPP
immediately after the SB DMA is flushed.

Change-Id: I3dc0792a50d7dec42cb32bf8cd1e3d0b217cf582
Signed-off-by: Christopher Braga <cbraga@codeaurora.org>

msm/sde/sde_color_processing.c

@@ -1547,6 +1547,7 @@ void sde_cp_dspp_flush_helper(struct sde_crtc *sde_crtc, u32 feature)
 			if (feature == SDE_CP_CRTC_DSPP_SB) {
 				if (!dspp->sb_dma_in_use)
 					continue;
+				dspp->sb_dma_in_use = false;
 
 				_flush_sb_dma_hw(active_ctls, ctl,
 						sizeof(active_ctls));