usb: otg: OMAP4430: Introducing suspend function for power management

Introduced the suspend/resume function for the OMAP4430 internal PHY.
This will be used by the twl6030-usb transceiver driver.
Moved the clock enable/disable function calls and power on/off of the PHY
code from power on/off functions to suspend/resume function.

Pass the suspend function through board data for OMAP4430sdp and OMAP4panda.
This will be used by the twl6030-usb transceiver driver.

Signed-off-by: Hema HK <hemahk@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>