drm/msm/dpu: Clear CTL_FETCH_PIPE_ACTIVE on mixer reset

drm/msm/dpu: Clear CTL_FETCH_PIPE_ACTIVE on mixer reset

Resetting mixers should also include resetting active fetch pipes.

Fixes: ae4d721ce100 ("drm/msm/dpu: add an API to reset the encoder related hw blocks")
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/651246/
Link: https://lore.kernel.org/r/20250430-b4-sm8750-display-v5-8-8cab30c3e4df@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>