fix(plat/st): improve DDR get size function

Avoid parsing device tree every time when returning
the DDR size.
A cache flush on this size is also added because TZC400 configuration
is applied at the end of BL2 after MMU and data cache being turned off.
Configuration needs to retrieve the DDR size to generate the correct
region. Access to the size fails because the value is still in the data
cache. Flushing the size is mandatory.

Change-Id: I3dd1958f37d806f9c15a5d4151968935f6fe642e
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
1 file changed