[ARM] Remove MT_DEVICE_IXP2000 and associated definitions

As of the previous commit, MT_DEVICE_IXP2000 encodes to the same
PTE bit encoding as MT_DEVICE, so it's now redundant.  Convert
MT_DEVICE_IXP2000 to use MT_DEVICE instead, and remove its aliases.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index 7193485..a809445 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -60,10 +60,9 @@
 #define MT_DEVICE		0
 #define MT_DEVICE_NONSHARED	1
 #define MT_DEVICE_CACHED	2
-#define MT_DEVICE_IXP2000	3
-#define MT_DEVICE_WC		4
+#define MT_DEVICE_WC		3
 /*
- * types 5 onwards can be found in asm/mach/map.h and are undefined
+ * types 4 onwards can be found in asm/mach/map.h and are undefined
  * for ioremap
  */