jtag: remove libftdi enum-compare warning

See Trac #52 for details.

Change-Id: Idb509ead2b51bfcceeb00d0224a4d1c395b28a04
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/801
Tested-by: jenkins
Reviewed-by: Olivier Schonken <olivier.schonken@gmail.com>
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>

src/jtag/drivers/ft2232.c

@@ -135,7 +135,7 @@ enum ftdi_interface {
  #if BUILD_FT2232_FTD2XX == 1
 	enum { FT_DEVICE_2232H = 6, FT_DEVICE_4232H, FT_DEVICE_232H };
  #elif BUILD_FT2232_LIBFTDI == 1
-	enum { TYPE_2232H = 4, TYPE_4232H = 5, TYPE_232H = 6 };
+	enum ftdi_chip_type { TYPE_2232H = 4, TYPE_4232H = 5, TYPE_232H = 6 };
  #endif
 #endif