ARM: OMAP3+: PRM: Enable IO wake up

Enable IO Wake up for OMAP3/4 as part of PRM Init. Currently this has been
managed in cpuidle path which is not the right place. Subsequent patch
will remove IO Daisy chain handling in cpuidle path once daisy chain is
handled as part of hwmod mux. This patch also moves the OMAP4 IO wakeup
enable code from the trigger function to init time setup.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Reviewed-by: Rajendra Nayak <rnayak@ti.com>
[paul@pwsan.com: harmonize function names with other PRM functions; add
 kerneldoc; resolve checkpatch warnings]
Signed-off-by: Paul Walmsley <paul@pwsan.com>