Use struct usb_otg members with OTG specific functions instead
of usb_phy members.

[ balbi@ti.com : fixed a compile error on isp1704_charger.c ]
Signed-off-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: NMarek Vasut <marek.vasut@gmail.com>
Acked-by: NNeil Zhang <zhangwm@marvell.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>