ARM: OMAP2+: omap_hwmod: Allow io_ring wakeup configuration for all modules

Some modules doesn't have SYSC_HAS_ENAWAKEUP bit available (ex: usb
host uhh module) in absence of this flag
omap_hwmod_enable/disable_wakeup avoids configuring pad mux wakeup
capability.

Configure sysc if SYSC_HAS_ENAWAKEUP is available and for other cases
try enabling/disabling wakeup from mux_pad pins.

Cc: Paul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
[paul@pwsan.com: updated function kerneldoc documentation]
Signed-off-by: Paul Walmsley <paul@pwsan.com>