This patch programs the Memory controller's control registers
to disable non-secure accesses to the TZRAM. In case these
registers are already programmed by the BL2/BL30, then the
driver just bails out.

Change-Id: Ia1416988050e3d067296373060c717a260499122
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>