OMAP3: PM: Added resched check into idle calls

Fixes a bug where scheduling is delayed until next wakeup due to race
condition (e.g. interrupt requests scheduling just before omap_sram_idle
is entered.)

Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>