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/configs/T4240RDB_defconfig b/configs/T4240RDB_defconfig
index 361769d..689b644 100644
--- a/configs/T4240RDB_defconfig
+++ b/configs/T4240RDB_defconfig
@@ -1,5 +1,5 @@
 CONFIG_PPC=y
-CONFIG_SYS_TEXT_BASE=0xEFF40000
+CONFIG_TEXT_BASE=0xEFF40000
 CONFIG_ENV_SIZE=0x2000
 CONFIG_ENV_SECT_SIZE=0x20000
 CONFIG_DEFAULT_DEVICE_TREE="t4240rdb"