soc: mediatek: pwrap: fix cipher init setting error

PWRAP_DEW_CIPHER_LOAD and PWRAP_DEW_CIPHER_START only exist at
PMIC_mt6397 datasheet. We fix it before merge PMIC_mt6351 driver.

Fixes: 5ae48040 ("soc: mediatek: PMIC wrap: add mt6323 slave support")

Signed-off-by: Argus Lin <argus.lin@mediatek.com>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>