usb: gadget: fusb300_udc: Fix memory leak of fusb300->ep[i]

There is no deallocation of fusb300->ep[i] elements, allocated at
fusb300_probe.

The patch adds deallocation of fusb300->ep array elements.

Signed-off-by: Young Xiao <92siuyang@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>