configure RTC PAD15
| X32P_FUN_IE | input enable in work mode |
| X32P_SLP_OE | output enable in sleep mode |
| X32P_SLP_IE | input enable in sleep mode |
| X32P_SLP_SEL | 1: enable sleep mode during sleep,0: no sleep mode |
| X32P_FUN_SEL | function sel |
| X32P_MUX_SEL | 1: use RTC GPIO,0: use digital GPIO |
| X32P_RUE | RUE |
| X32P_RDE | RDE |
| X32P_DRV | DRV |