phy: phy-rockchip-samsung-hdptx-hdmi: Add clock provider

The HDMI PHY PLL can be used as an alternative dclk source to SoC CRU.
It provides more accurate clock rates required to properly support
various display modes, e.g. those relying on non-integer refresh rates.

Also note this only works for HDMI 2.0 or bellow, e.g. cannot be used to
support HDMI 2.1 4K@120Hz mode.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Hacked-by: Steven Price