drm/msm/disp/dpu1: add flags to indicate obsolete irqs

Some irqs which are applicable for sdm845 target are no
longer applicable for sc7180 and sc7280 targets. Add a
flag to indicate the irqs which are obsolete for a
particular target so that these irqs are skipped while
checking for matching irq lookup index.

Signed-off-by: Krishna Manikandan <mkrishn@codeaurora.org>
Link: https://lore.kernel.org/r/1617688895-26275-4-git-send-email-mkrishn@codeaurora.org
Signed-off-by: Rob Clark <robdclark@chromium.org>