stm32mp1: configure boot-on and always-on regulators after DDR init

configure_pmic() is in charge of setting voltages and enabling regulators
if they are defined in DT with "boot-on" or "always-on" properties. This is
done one after the other.
It has to be executed after DDR initialization, which setups its own
regulator rampings, with specified order and delays.

Change-Id: If714d471bc78e292b9079f56f7a7b9982623573f
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>
Reviewed-on: https://gerrit.st.com/c/mpu/oe/st/tf-a/+/158644


Reviewed-by: CITOOLS <smet-aci-reviews@lists.codex.cro.st.com>
Reviewed-by: CIBUILD <smet-aci-builds@lists.codex.cro.st.com>
Reviewed-by: Yann GAUTIER <yann.gautier@st.com>