usb: dwc2: Remove unnecessary kfree

commit cd4b1e34 upstream.

This shouldn't be freed by the HCD as it is owned by the core and
allocated with devm_kzalloc.

Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>