To mask the time consumed waiting for CMPCR_READY bit, the function to
enable IO compensation is split in 2, a start and a finish function.
This is used at boot, and in return from STOP mode.

Change-Id: Ic2b67c0e68415eb1abd3c7ba916b0fae21737235
Signed-off-by: Yann Gautier <yann.gautier@st.com>
Reviewed-on: https://gerrit.st.com/c/mpu/oe/st/tf-a/+/188608


Reviewed-by: CITOOLS <MDG-smet-aci-reviews@list.st.com>
Reviewed-by: CIBUILD <MDG-smet-aci-builds@list.st.com>