Peri backup control register
| FLOW_ERR | backup error type |
| START | backup start signal |
| TO_MEM | backup direction(reg to mem / mem to reg) |
| LINK_SEL | Link select |
| START_MAC | mac sw backup start signal |
| TO_MEM_MAC | mac sw backup direction(reg to mem / mem to reg) |
| SEL_MAC | mac hw/sw select |