drm/msm/dpu: replace BIT(x) with correspond marco define string

To improve code readability, this patch replace BIT(x) with
correspond register bit define string

Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/476280/
Link: https://lore.kernel.org/r/1645824192-29670-3-git-send-email-quic_khsieh@quicinc.com


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>