drm: bridge: samsung-dsim: enter display mode in the enable() callback

The synaptics-r63353 (panel-bridge) can only be configured in command mode.
So, samsung-dsim (bridge) must not be in display mode during the
prepare()/unprepare() of the panel-bridge. Setting the
"pre_enable_prev_first" flag to true allows the prepare() of the
panel-bridge to be called between the pre_enabled() and enabled() of the
bridge. So, the bridge can enter display mode only in the enabled().
The unprepare() of the panel-bridge is instead called between the disable()
and post_disable() of the bridge. So, the disable() must exit the display
mode (i .e. enter command mode) to allow the panel-bridge to receive DSI
commands.

samsung_dsim_atomic_pre_enable   -> command mode
r63353_panel_prepare             -> send DSI commands
samsung_dsim_atomic_enable       -> enter display mode

samsung_dsim_atomic_disable      -> exit display mode (command mode)
r63353_panel_unprepare           -> send DSI commands
samsung_dsim_atomic_post_disable

Co-developed-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231218084354.508942-2-dario.binacchi@amarulasolutions.com