pxa: Disable dcache on palmld, palmtc, zipitz2

These platforms don't include dcache support. Define CONFIG_SYS_DCACHE_OFF
so that functions don't try to call non-existent routines like
flush_dcache_range().

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

include/configs/palmld.h

@@ -28,6 +28,9 @@
 #define	CONFIG_CPU_PXA27X		1	/* Marvell PXA270 CPU */
 #define	CONFIG_PALMLD		1	/* Palm LifeDrive board */
 
+/* we will never enable dcache, because we have to setup MMU first */
+#define CONFIG_SYS_DCACHE_OFF
+
 /*
  * Environment settings
  */

include/configs/palmtc.h

@@ -30,6 +30,9 @@
 #define	CONFIG_CPU_PXA25X			1	/* Intel PXA255 CPU */
 #define	CONFIG_PALMTC			1	/* Palm Tungsten|C board */
 
+/* we will never enable dcache, because we have to setup MMU first */
+#define CONFIG_SYS_DCACHE_OFF
+
 /*
  * Environment settings
  */

include/configs/zipitz2.h

@@ -41,6 +41,9 @@
 #define CONFIG_ENV_ADDR			0x40000
 #define CONFIG_ENV_SIZE			0x20000
 
+/* we will never enable dcache, because we have to setup MMU first */
+#define CONFIG_SYS_DCACHE_OFF
+
 #define	CONFIG_SYS_MALLOC_LEN		(128*1024)
 #define	CONFIG_ARCH_CPU_INIT