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/arch/powerpc/lib/board.c b/arch/powerpc/lib/board.c
index 529f719..fee8257 100644
--- a/arch/powerpc/lib/board.c
+++ b/arch/powerpc/lib/board.c
@@ -734,7 +734,7 @@
 
 # if defined(CONFIG_OXC) || defined(CONFIG_RMU)
 	/* flash mapped at end of memory map */
-	bd->bi_flashoffset = TEXT_BASE + flash_size;
+	bd->bi_flashoffset = CONFIG_SYS_TEXT_BASE + flash_size;
 # elif CONFIG_SYS_MONITOR_BASE == CONFIG_SYS_FLASH_BASE
 	bd->bi_flashoffset = monitor_flash_len;	/* reserved area for startup monitor  */
 # endif