usb/gadget/pch_udc: Fix compile error

Greg's e-mail address was old. So, I resend it.

Though I've tested this patch,
http://marc.info/?l=linux-usb&m=132825305710285&w=2,
I've received the following reports.
http://kisskb.ellerman.id.au/kisskb/buildresult/5771890/
http://kisskb.ellerman.id.au/kisskb/buildresult/5771905/

So, I added header file for these symbols.
Using this patch, this compile error must be disappeared.
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Tomoya MORINAGA <tomoya.rohm@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/pch_udc.c

@@ -16,6 +16,7 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 #include <linux/gpio.h>
+#include <linux/irq.h>
 
 /* GPIO port for VBUS detecting */
 static int vbus_gpio_port = -1;		/* GPIO port number (-1:Not used) */