[PATCH] Have core/drivers.c include <linux/gfp.h>

Currently, drivers/usb/core/drivers.c includes <linux/mm.h> to get at
<linux/gfp.h>.  The following includes <linux/gfp.h> directly.

drivers/usb/core/drivers.c

@@ -35,7 +35,7 @@
  */
 
 #include <linux/fs.h>
-#include <linux/mm.h>
+#include <linux/gfp.h>
 #include <linux/usb.h>
 #include <linux/usbdevice_fs.h>
 #include <linux/smp_lock.h>