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/board/BuS/EB+MCF-EV123/config.mk b/board/BuS/EB+MCF-EV123/config.mk
index f03e396..50185ae 100644
--- a/board/BuS/EB+MCF-EV123/config.mk
+++ b/board/BuS/EB+MCF-EV123/config.mk
@@ -23,6 +23,6 @@
 #
 
 sinclude $(OBJTREE)/board/$(BOARDDIR)/textbase.mk
-ifndef TEXT_BASE
-TEXT_BASE = 0xFE000000
+ifndef CONFIG_SYS_TEXT_BASE
+CONFIG_SYS_TEXT_BASE = 0xFE000000
 endif