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/verdin-imx8mp_defconfig b/configs/verdin-imx8mp_defconfig
index 932baa5..0179792 100644
--- a/configs/verdin-imx8mp_defconfig
+++ b/configs/verdin-imx8mp_defconfig
@@ -1,6 +1,6 @@
 CONFIG_ARM=y
 CONFIG_ARCH_IMX8M=y
-CONFIG_SYS_TEXT_BASE=0x40200000
+CONFIG_TEXT_BASE=0x40200000
 CONFIG_SPL_GPIO=y
 CONFIG_SPL_LIBCOMMON_SUPPORT=y
 CONFIG_SPL_LIBGENERIC_SUPPORT=y