drm/mediatek: do mtk_hdmi_send_infoframe after HDMI clock enable

The mtk_hdmi_send_infoframe have to
be run after PLL and PIXEL clock of HDMI enable.
Make sure that HDMI inforframes can be sent
successfully.

Signed-off-by: Junzhi Zhao <junzhi.zhao@mediatek.com>
Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>