Tegra186: save/restore BL31 context to/from TZDRAM

Tegra186: save/restore BL31 context to/from TZDRAM

This patch adds support to save the BL31 state to the TZDRAM
before entering system suspend. The TZRAM loses state during
system suspend and so we need to copy the entire BL31 code to
TZDRAM before entering the state.

In order to restore the state on exiting system suspend, a new
CPU reset handler is implemented which gets copied to TZDRAM
during boot. TO keep things simple we use this same reset handler
for booting secondary CPUs too.

Change-Id: I770f799c255d22279b5cdb9b4d587d3a4c54fad7
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>