drm/rcar-du: dsi: Respect DSI mode flags

drm/rcar-du: dsi: Respect DSI mode flags

Cache DSI mode flags in new mode_flags member of struct rcar_mipi_dsi .
Configure TXVMSETR register based on the content of DSI mode flags in
case the controller operates in video mode.

Rename TXVMSETR_H..BPEN_EN to TXVMSETR_H..BPEN and drop TXVMSETR_H..BPEN_DIS
which resolves to 0. Update TXVMSETR_VSEN in the same manner. Replace
TXVMSETR_SYNSEQ_PULSES with a code comment next to TXVMSETR_SYNSEQ_EVENTS
because TXVMSETR_SYNSEQ_PULSES resolves to 0.

Do not convert bits and bitfields to BIT() and GENMASK() yet, to be
consisten with the current style. Conversion to BIT() and GENMASK()
macros is done at the very end of this series in the last two patches.

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Link: https://patch.msgid.link/20251028232959.109936-9-marek.vasut+renesas@mailbox.org
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>