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/sandbox_vpl_defconfig b/configs/sandbox_vpl_defconfig
index 8128f6e..a2a1295 100644
--- a/configs/sandbox_vpl_defconfig
+++ b/configs/sandbox_vpl_defconfig
@@ -1,4 +1,4 @@
-CONFIG_SYS_TEXT_BASE=0x200000
+CONFIG_TEXT_BASE=0x200000
 CONFIG_SPL_LIBCOMMON_SUPPORT=y
 CONFIG_SPL_LIBGENERIC_SUPPORT=y
 CONFIG_NR_DRAM_BANKS=1