drm/panel: st7703: Assert reset prior to powering down the regulators

The reset pin is inverted, so if we don't assert reset, the actual gpio
will be high and may keep driving the IO port of the panel.
Signed-off-by: NOndrej Jirman <megous@megous.com>
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>
Tested-by: NGuido Günther <agx@sigxcpu.org>
Reviewed-by: NGuido Günther <agx@sigxcpu.org>
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200701162928.1638874-12-megous@megous.com

drivers/gpu/drm/panel/panel-sitronix-st7703.c

@@ -415,6 +415,7 @@ static int st7703_unprepare(struct drm_panel *panel)
 	if (!ctx->prepared)
 		return 0;
 
+	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
 	regulator_disable(ctx->iovcc);
 	regulator_disable(ctx->vcc);
 	ctx->prepared = false;