drm/msm/dpu: remove struct dpu_encoder_irq

drm/msm/dpu: remove struct dpu_encoder_irq

Remove additional indirection: specify IRQ callbacks and IRQ indices
directly rather than through the pointer in the irq structure. For each
IRQ we have a constant IRQ callback. This change simplifies code review
as the reader no longer needs to remember which function is called.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/474700/
Link: https://lore.kernel.org/r/20220217043148.480898-6-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>