drm/bridge: tc358767: Check if fully initialized before signalling HPD event via IRQ

Make sure the connector is fully initialized before signalling any
HPD events via drm_kms_helper_hotplug_event(), otherwise this may
lead to NULL pointer dereference.
Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240531203333.277476-1-marex@denx.de

drivers/gpu/drm/bridge/tc358767.c

@@ -2152,7 +2152,7 @@ static irqreturn_t tc_irq_handler(int irq, void *arg)
 		dev_err(tc->dev, "syserr %x\n", stat);
 	}
 
-	if (tc->hpd_pin >= 0 && tc->bridge.dev) {
+	if (tc->hpd_pin >= 0 && tc->bridge.dev && tc->aux.drm_dev) {
 		/*
 		 * H is triggered when the GPIO goes high.
 		 *