ARM: OMAP3: CPUidle: Make use of CPU PM notifiers

Save VFP CPU context using CPU PM notifier chain. VFP context
is lost when CPU hits OFF state.

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-by: Vishwanath BS <vishwanath.bs@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>