habanalabs/gaudi: fix debugfs dma channel selection

Do not use a dma channel for debugfs requested transfer if it's
QM is not idle.

Signed-off-by: Guy Zadicario <gzadicario@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>