clk: stm32mp1: enable kernel clocks before entering in stop mode

We have to enable kernel clocks before entering in stop mode
and clear them at resume.
In standby mode stm32mp1_clock_stopmode_save() is called before,
then it's not necessary to enable them in stm32mp1_clock_suspend().

Change-Id: I0099028be5ea036cb8fcbd3bc868b5e73eec76b3
Signed-off-by: Gabriel Fernandez <gabriel.fernandez@st.com>
Reviewed-on: https://gerrit.st.com/c/mpu/oe/st/tf-a/+/159064


Reviewed-by: CITOOLS <smet-aci-reviews@lists.codex.cro.st.com>
Reviewed-by: CIBUILD <smet-aci-builds@lists.codex.cro.st.com>
Reviewed-by: Lionel DEBIEVE <lionel.debieve@st.com>
Reviewed-by: Yann GAUTIER <yann.gautier@st.com>
Reviewed-by: Erwan LE RAY <erwan.leray@st.com>
Tested-by: Erwan LE RAY <erwan.leray@st.com>