OMAP3: PM: save secure RAM only during init

The function omap3_save_secure_ram() is now called only once during
the initialization of the device and consequent sleep cycles will
re-use the same saved contents for secure RAM. Users who need secure
services should do secure RAM saving before entering off-mode, if a
secure service has been accessed after last save.

There are both latency and reliability issues with saving secure RAM
context in the idle path. The context save uses a hardware resource
which takes an order of hundreds of milliseconds to initialize after a
wake up from off-mode, and also there is no way of checking whether it
is ready from kernel side or not. It just crashes if you use it too
quickly

Additional fix to ensure scratchpad save is done after secure
RAM by Roger Quadros.

Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
Signed-off-by: Roger Quadros <ext-roger.quadros@nokia.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>