usb: musb: Using runtime pm APIs for musb.

Calling runtime pm APIs pm_runtime_put_sync() and pm_runtime_get_sync()
for enabling/disabling the clocks, sysconfig settings.

Enable clock, configure no-idle/standby when active and configure force idle/standby
and disable clock when idled. This is taken care by the runtime framework when
driver calls the pm_runtime_get_sync and pm_runtime_put_sync APIs.
Need to configure MUSB into force standby and force idle mode when usb not used

Signed-off-by: Hema HK <hemahk@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Cousson, Benoit <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>