USB: r8a66597-udc: Initialize uninitialized variable, fix compile warning

In today linux-next I got a compile warning due a possible uninitialized variable

This patch solves the issue initializing the variable
Signed-off-by: Javier Martinez Canillas <martinez.javier@gmail.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Magnus Damm <damm@opensource.se>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/r8a66597-udc.h

@@ -136,7 +136,7 @@ static inline void r8a66597_read_fifo(struct r8a66597 *r8a66597,
 				      int len)
 {
 	void __iomem *fifoaddr = r8a66597->reg + offset;
-	unsigned int data;
+	unsigned int data = 0;
 	int i;
 
 	if (r8a66597->pdata->on_chip) {