USB: remove unneeded idr.h include

None of these USB files need idr.h, so don't include it.

Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/musb_core.c

@@ -99,7 +99,6 @@
 #include <linux/prefetch.h>
 #include <linux/platform_device.h>
 #include <linux/io.h>
-#include <linux/idr.h>
 #include <linux/dma-mapping.h>
 
 #include "musb_core.h"