mfd: TWL6030: OMAP4: Registering the TWL6030-usb device

Registering the twl6030-usb transceiver device as a child to twl6030 core.
Removed the NOP transceiver init call from board file.

Populated twl4030_usb_data platform data structure with the function
pointers for OMAP4430 internal PHY operation to be used by twl630-usb driver.

Signed-off-by: Hema HK <hemahk@ti.com>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>