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/pxa255_idp/config.mk b/board/pxa255_idp/config.mk
index 55c8b27..f30f695 100644
--- a/board/pxa255_idp/config.mk
+++ b/board/pxa255_idp/config.mk
@@ -1,3 +1,3 @@
-#TEXT_BASE = 0xa1700000
-TEXT_BASE = 0xa3080000
-#TEXT_BASE = 0
+#CONFIG_SYS_TEXT_BASE = 0xa1700000
+CONFIG_SYS_TEXT_BASE = 0xa3080000
+#CONFIG_SYS_TEXT_BASE = 0