staging: vchiq_debugfs: Use forward declarations

Use forward declarations for struct vchiq_state and vchiq_instance.
We can then drop the vchiq_core.h header from vchiq_debugfs.h.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Link: https://lore.kernel.org/r/20241107194806.90408-4-umang.jain@ideasonboard.com


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