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/lpd7a40x/config.mk b/board/lpd7a40x/config.mk
index bc03874..003e707 100644
--- a/board/lpd7a40x/config.mk
+++ b/board/lpd7a40x/config.mk
@@ -34,5 +34,5 @@
 # download area is 0xc0f00000
 #
 
-TEXT_BASE = 0xc1fc0000
-#TEXT_BASE = 0x00000000
+CONFIG_SYS_TEXT_BASE = 0xc1fc0000
+#CONFIG_SYS_TEXT_BASE = 0x00000000