driver core: platform: fix race condition with driver_override

The driver_override implementation is susceptible to race condition when
different threads are reading vs storing a different driver override.
Add locking to avoid race condition.

Fixes: 3d713e0e382e ("driver core: platform: add device binding path 'driver_override'")
Cc: stable@vger.kernel.org
Signed-off-by: Adrian Salido <salidoa@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
void __init early_platform_cleanup(void)
{
	struct platform_device *pd, *pd2;

	/* clean up the devres list used to chain devices */
	list_for_each_entry_safe(pd, pd2, &early_platform_device_list,
				 dev.devres_head) {
		list_del(&pd->dev.devres_head);
		memset(&pd->dev.devres_head, 0, sizeof(pd->dev.devres_head));
	}
}

void __init early_platform_cleanup(void)
{
	struct platform_device *pd, *pd2;

	/* clean up the devres list used to chain devices */
	list_for_each_entry_safe(pd, pd2, &early_platform_device_list,
				 dev.devres_head) {
		list_del(&pd->dev.devres_head);
		memset(&pd->dev.devres_head, 0, sizeof(pd->dev.devres_head));
	}
}
