staging: vc04_services: vchiq_arm: Fix NULL ptr dereferences

The commit 8c9753f ("staging: vc04_services: vchiq_arm: Drop
g_cache_line_size") introduced NULL pointer dereferences by
using the wrong device.

Fixes: 8c9753f ("staging: vc04_services: vchiq_arm: Drop g_cache_line_size")
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Link: https://lore.kernel.org/r/20240420091240.9552-1-wahrenst@gmx.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c

@@ -257,7 +257,7 @@ create_pagelist(struct vchiq_instance *instance, char *buf, char __user *ubuf,
 	if (count >= INT_MAX - PAGE_SIZE)
 		return NULL;
 
-	drv_mgmt = dev_get_drvdata(instance->state->dev->parent);
+	drv_mgmt = dev_get_drvdata(instance->state->dev);
 
 	if (buf)
 		offset = (uintptr_t)buf & (PAGE_SIZE - 1);
@@ -436,7 +436,7 @@ free_pagelist(struct vchiq_instance *instance, struct vchiq_pagelist_info *pagel
 
 	dev_dbg(instance->state->dev, "arm: %pK, %d\n", pagelistinfo->pagelist, actual);
 
-	drv_mgmt = dev_get_drvdata(instance->state->dev->parent);
+	drv_mgmt = dev_get_drvdata(instance->state->dev);
 
 	/*
 	 * NOTE: dma_unmap_sg must be called before the