drm/msm/dpu: Simplify using local 'ctl' variable

In few places we store 'phys_enc->hw_ctl' to local 'ctl' variable so use
it everywhere.  No functional change.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/632389/
Link: https://lore.kernel.org/r/20250114155959.583889-1-krzysztof.kozlowski@linaro.org


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