phy: mediatek: phy-mtk-hdmi: Register PHY provided regulator

phy: mediatek: phy-mtk-hdmi: Register PHY provided regulator

At least version 2 of the HDMI PHY, found in MediaTek MT8195 and
MT8188 SoCs, does provide hardware support to switch on/off the
HDMI 5V pins (which are also used for DDC), and this translates
to this being a fixed regulator.

Register this PHY-provided regulator so that it can be fed to the
hdmi-connector driver to manage the HDMI +5V PWR rail.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20241120124143.132637-1-angelogioacchino.delregno@collabora.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>