staging: vchiq_arm: Avoid NULL ptr deref in vchiq_dump_platform_instances

vchiq_get_state() can return a NULL pointer. So handle this cases and
avoid a NULL pointer derefence in vchiq_dump_platform_instances.

Reviewed-by: Nicolas Saenz Julienne <nsaenz@kernel.org>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Link: https://lore.kernel.org/r/1642968143-19281-17-git-send-email-stefan.wahren@i2se.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>