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/Marvell/openrd_base/config.mk b/board/Marvell/openrd_base/config.mk
index 8ae355e..5a49280 100644
--- a/board/Marvell/openrd_base/config.mk
+++ b/board/Marvell/openrd_base/config.mk
@@ -27,7 +27,7 @@
 # MA 02110-1301 USA
 #
 
-TEXT_BASE = 0x00600000
+CONFIG_SYS_TEXT_BASE = 0x00600000
 
 # Kirkwood Boot Image configuration file
 KWD_CONFIG = $(SRCTREE)/board/$(BOARDDIR)/kwbimage.cfg