usb: gadget: pxa25x: make it compile with debug again

|drivers/usb/gadget/pxa25x_udc.h: In function 'dump_state':
|drivers/usb/gadget/pxa25x_udc.h:228:20: error: invalid type argument of '->' (have 'struct usb_ep')

Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>