drm/sun4i: Add support for Synopsys HDMI PHY

Currently sun8i-hdmi-phy driver supports only custom PHYs connected to
DW HDMI controller. Since newest Allwinner SoCs have unmodified Synopsys
PHY, driver has to be reorganized to support them.

Variant structure is expanded to allow differentiation between custom
and Sysnopsys PHYs and to hold Synopsys PHY settings.

Since DW HDMI bridge platform data has different fields for custom and
Sysnopsys PHY, function sun8i_hdmi_phy_get_ops() is replaced with
sun8i_hdmi_phy_set_ops().

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181104182705.18047-22-jernej.skrabec@siol.net