uart, gpio, wd_timer and i2c does support the new smart-idle with wakeup
added in OMAP4.

Add the flag to allow the hwmod core to enable this mode when applicable.
Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Rajendra Nayak <rnayak@ti.com>