habanalabs: move memory_scrub_val to hdev struct

move the field memory_scrub_val from struct hl_dbg_device_entry
to struct hl_device. This is because we want to use
this field also if debugfs is off.

Signed-off-by: Dafna Hirschfeld <dhirschfeld@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>