OMAP3: PM: SDRC auto-refresh workaround for off-mode

Errata: ES3.0, ES3.1 SDRC not sending auto-refresh when OMAP wakes-up
from OFF mode

Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@digia.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>