drm/panel: p079zca: Add variable unprepare_delay properties

When panel power down, p079zca need delay between reset and disable
power supply, but p097pfg does not need it. Similarly p097zca needs
a delay after entering panel sleep mode. So add two delay properties,
so we can meet these two panel power down sequence.

Signed-off-by: Lin Huang <[e-mail]>
[add sleep-mode delay]
Signed-off-by: Heiko Stuebner <[e-mail]>
Signed-off-by: Thierry Reding <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/panel/panel-innolux-p079zca.c

···
 	unsigned int lanes;
 	const char * const *supply_names;
 	unsigned int num_supplies;
+	unsigned int sleep_mode_delay;
+	unsigned int power_down_delay;
 };
 
 struct innolux_panel {
···
 		return err;
 	}
 
+	if (innolux->desc->sleep_mode_delay)
+		msleep(innolux->desc->sleep_mode_delay);
+
 	gpiod_set_value_cansleep(innolux->enable_gpio, 0);
 
-	/* T8: 80ms - 1000ms */
-	msleep(80);
+	if (innolux->desc->power_down_delay)
+		msleep(innolux->desc->power_down_delay);
 
 	err = regulator_bulk_disable(innolux->desc->num_supplies,
 				     innolux->supplies);
···
 	.lanes = 4,
 	.supply_names = innolux_p079zca_supply_names,
 	.num_supplies = ARRAY_SIZE(innolux_p079zca_supply_names),
+	.power_down_delay = 80, /* T8: 80ms - 1000ms */
 };
 
 static int innolux_panel_get_modes(struct drm_panel *panel)