Rename CONFIG_SYS_TEXT_BASE to CONFIG_TEXT_BASE

The current name is inconsistent with SPL which uses CONFIG_SPL_TEXT_BASE
and this makes it imposible to use CONFIG_VAL().

Rename it to resolve this problem.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/configs/at91sam9260ek.h b/include/configs/at91sam9260ek.h
index ef9335c..ca5815f 100644
--- a/include/configs/at91sam9260ek.h
+++ b/include/configs/at91sam9260ek.h
@@ -17,7 +17,7 @@
 #include <asm/hardware.h>
 
 /*
- * Warning: changing CONFIG_SYS_TEXT_BASE requires
+ * Warning: changing CONFIG_TEXT_BASE requires
  * adapting the initial boot program.
  * Since the linker has to swallow that define, we must use a pure
  * hex number here!