Rename TEXT_BASE into CONFIG_SYS_TEXT_BASE

The change is currently needed to be able to remove the board
configuration scripting from the top level Makefile and replace it by
a simple, table driven script.

Moving this configuration setting into the "CONFIG_*" name space is
also desirable because it is needed if we ever should move forward to
a Kconfig driven configuration system.

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/include/configs/smdk6400.h b/include/configs/smdk6400.h
index 624fe04..451b534 100644
--- a/include/configs/smdk6400.h
+++ b/include/configs/smdk6400.h
@@ -51,7 +51,7 @@
 /* input clock of PLL: SMDK6400 has 12MHz input clock */
 #define CONFIG_SYS_CLK_FREQ	12000000
 
-#if !defined(CONFIG_NAND_SPL) && (TEXT_BASE >= 0xc0000000)
+#if !defined(CONFIG_NAND_SPL) && (CONFIG_SYS_TEXT_BASE >= 0xc0000000)
 #define CONFIG_ENABLE_MMU
 #endif