drivers: Rename 'libusb1_common' to 'libusb_helper'

The name 'common' does not make sense anymore. While at it,
remove some unnecessary #includes.

Change-Id: If9798a5cce179438d89428a598d8ca05c8e5f20c
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: http://openocd.zylin.com/5434
Tested-by: jenkins
Reviewed-by: Oleksij Rempel <linux@rempel-privat.de>

src/jtag/aice/aice_interface.c

@@ -25,7 +25,6 @@
 #include <transport/transport.h>
 #include <target/target.h>
 #include <jtag/aice/aice_transport.h>
-#include <jtag/drivers/libusb_common.h>
 #include "aice_usb.h"
 
 #define AICE_KHZ_TO_SPEED_MAP_SIZE	16

src/jtag/aice/aice_usb.c

@@ -19,7 +19,7 @@
 #include "config.h"
 #endif
 
-#include <jtag/drivers/libusb_common.h>
+#include <jtag/drivers/libusb_helper.h>
 #include <helper/log.h>
 #include <helper/time_support.h>
 #include <target/target.h>