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/imx28_xea_defconfig b/configs/imx28_xea_defconfig
index dcb2f4e..48be3c5 100644
--- a/configs/imx28_xea_defconfig
+++ b/configs/imx28_xea_defconfig
@@ -1,7 +1,7 @@
 CONFIG_ARM=y
 CONFIG_SPL_SYS_THUMB_BUILD=y
 CONFIG_ARCH_MX28=y
-CONFIG_SYS_TEXT_BASE=0x40002000
+CONFIG_TEXT_BASE=0x40002000
 CONFIG_SYS_MALLOC_F_LEN=0x800
 CONFIG_SPL_GPIO=y
 CONFIG_SPL_LIBCOMMON_SUPPORT=y