musb can be suspended at the time some other driver wants to do ulpi
transfers using usb_phy_io_* functions, and that can cause data abort,
as it happened with isp1704_charger:
http://article.gmane.org/gmane.linux.kernel/1226122

Add pm_runtime to ulpi functions to rectify this. This also adds io_dev
to usb_phy so that pm_runtime_* functions can be used.

Cc: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>