The encoder .mode_fixup() operation is legacy, atomic updates uses the
new .atomic_check() operation. Convert the encoders drivers.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

The atomic connector DPMS helper implements the connector DPMS operation
using atomic commit, removing the need for DPMS helper operations on
CRTCs and encoders.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

This removes the legacy mode config code. The CRTC and encoder prepare
and commit operations are not used anymore, remove them.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

When using atomic updates the encoder .enable() and .disable() helper
operations are preferred over the (then legacy) .prepare() and .commit()
operations. Implement .enable() and .disable() and rework .prepare(),
.commit() and .dpms() as wrappers around .enable() and .disable(),
easing their future removal.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

The LVDS encoder doesn't support DPMS states, replace the DPMS operation
by enable/disable to avoid propagating DPMS states down to the encoder
code.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

The intermediate DPMS standby and suspend states are a thing from the
past. They only matter in practice for VGA CRT monitors, and are just a
power saving vs. resume time optimization. Given that they have never
been implemented properly in the rcar-du driver and that the Intel
driver has dropped them on the vga port years ago, it's safe to only
care about the on and off states.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

The rcar-du driver refuses connecting an LVDS output to an HDMI encoder.
There is not technical reason for that restriction, remove it.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

SoCs that integrate the DU have no internal HDMI encoder, support
external encoders only.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>