usb: cdns3: ep0: Fix build warnings related to cache ops

Since, commit 62f9b654 ("common: Move older CPU functions to their own header")
cache ops functions are declared in a separate header. Include the same
to avoid build warnings.
Signed-off-by: NVignesh Raghavendra <vigneshr@ti.com>

drivers/usb/cdns3/ep0.c

@@ -10,6 +10,7 @@
  *          Peter Chen <peter.chen@nxp.com>
  */
 
+#include <cpu_func.h>
 #include <linux/usb/composite.h>
 #include <linux/iopoll.h>