Beside standard suspend-to-RAM state, Zynq MPSoC supports
suspend-to-RAM state with additional power savings, called
power-off suspend-to-RAM. If this mode is set, only NODE_EXTERN
must be set as wake source. Standard suspend-to-RAM procedure
is unchanged.

This patch adds support for setting suspend mode from higher
ELs and ensuring that all conditions for power-off suspend mode
are set.

Signed-off-by: Siva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com>
Signed-off-by: Filip Drazic <filip.drazic@aggios.com>