usb: dwc2: Remove '0x' notation when using %pad format

%pad notation automatically prints in hexadecimal format (with '0x'), so remove
the unneeded '0x' to avoid a '0x0x' string.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>