OMAP3: PM: Enable IO / IO-CHAIN wakeups for PER

IO events can also come from GPIO modules, which reside in the PER domain.
It is possible for the PER to enter RET while CORE is still in ON.
If GPIO 2-6 are enabled for IO-pad wakeups, the PER domain will not
wakeup in this case, unless we enable it.

Signed-off-by: Mike Chan <mike@android.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>