cpu clock config register
| CPUPERIOD_SEL | This field used to sel cpu clock frequent. |
| PLL_FREQ_SEL | This field used to sel pll frequent. |
| CPU_WAIT_MODE_FORCE_ON | Set 1 to force cpu_waiti_clk enable. |
| CPU_WAITI_DELAY_NUM | This field used to set delay cycle when cpu enter waiti mode, after delay waiti_clk will close |