drm/msm/dpu: Disable autorefresh in command mode

When a command mode display is used, it may be retaining the bootloader
configuration which, in most of the cases, enables the autorefresh
feature in order to keep the splash up.

Since there is no autorefresh management in this driver, wire up the
autorefresh ops in the dpu_hw_pingpong and disable the feature when
preparing for cmd commit: instead of disabling it when initializing
the command mode, this road was chosen as to open future possibility
of enabling and managing the autorefresh feature in the driver.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>