drm/msm/dpu: rename dpu_hw_setup_vsync_source functions

Rename dpu_hw_setup_vsync_source functions to make the names match the
implementation: on DPU 5.x the TOP only contains timer setup, while 3.x
and 4.x used MDP_VSYNC_SEL register to select TE source.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/598745/
Link: https://lore.kernel.org/r/20240613-dpu-handle-te-signal-v2-8-67a0116b5366@linaro.org