phy: mediatek: statify mtk_hdmi_phy_driver

mtk_hdmi_phy_driver is not declared as static, so statify it.

drivers/phy/mediatek/phy-mtk-hdmi.c:204:24: warning: symbol 'mtk_hdmi_phy_driver' was not declared. Should it be static?

Acked-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Link: https://lore.kernel.org/r/20201205091146.3184305-1-vkoul@kernel.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>