USB: otg: adding nop usb transceiver

NOP transceiver is used by all the usb transceiver which are mostly
autonomous and doesn't require any programming or which are built
into the usb ip itself.NOP transceiver only allocates the memory
for struct xceiv and calls otg_set_transceiver() so function call
to otg_get_transceiver() will return a valid transceiver.

NOP transceiver device should be registered by calling
usb_nop_xceiv_register() from platform files.

Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Cc: Felipe Balbi <felipe.balbi@nokia.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>