Do not dereference nyx_device struct after closing module

nyx_module_close (close_ptr) function releases the memory of nyx_device (d),
so do not dereference/touch that dangling pointer after close

Open-webOS-DCO-1.0-Signed-off-by: Janne Kiiski <janne.kiiski@palm.com>

Change-Id: I1511d2ea2fe6dc3694348e2f5af97fdeb8033174