debugfs: show current idle state of gpu pipeline

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
we need to write the physical address into VIVS_FE_COMMAND_ADDRESS

Looks like our simple ring buffer gets executed :)

cat /sys/kernel/debug/dri/1/gpu
134000.gpu2d Status:
        rb_iova: 0x0880000000
        idle: 0x087ffffffe
FE is not idle

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>