powerpc: MPC8572DS: Remove macro CONFIG_MPC8572DS

Use CONFIG_TARGET_MPC8572DS instead.

Signed-off-by: York Sun <york.sun@nxp.com>
diff --git a/board/freescale/common/pixis.h b/board/freescale/common/pixis.h
index 3c59157..df3cc09 100644
--- a/board/freescale/common/pixis.h
+++ b/board/freescale/common/pixis.h
@@ -73,7 +73,7 @@
 	u8 res2[34];
 } __attribute__ ((packed)) pixis_t;
 
-#elif defined(CONFIG_MPC8572DS)
+#elif defined(CONFIG_TARGET_MPC8572DS)
 typedef struct pixis {
 	u8 id;
 	u8 ver;