drm/msm/dpu: get rid of dpu_encoder_helper_(un)register_irq

drm/msm/dpu: get rid of dpu_encoder_helper_(un)register_irq

Get rid of dpu_encoder_helper_register_irq/unregister_irq helpers, call
dpu_core_register/unregister_callback directly, without surrounding them
with helpers.

Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/474698/
Link: https://lore.kernel.org/r/20220217043148.480898-5-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>