drm/mediatek: dsi: Use IRQF_TRIGGER_NONE for dsi irq trigger type

The interrupt trigger is already set by OF. When do devm_request_irq()
in driver, please use IRQF_TRIGGER_NONE and don't specify trigger type
again.

Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>