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/mt7981_sd_rfb_defconfig b/configs/mt7981_sd_rfb_defconfig
index 2a66a28..5e0c8c8 100644
--- a/configs/mt7981_sd_rfb_defconfig
+++ b/configs/mt7981_sd_rfb_defconfig
@@ -1,7 +1,7 @@
 CONFIG_ARM=y
 CONFIG_POSITION_INDEPENDENT=y
 CONFIG_ARCH_MEDIATEK=y
-CONFIG_SYS_TEXT_BASE=0x41e00000
+CONFIG_TEXT_BASE=0x41e00000
 CONFIG_SYS_MALLOC_F_LEN=0x4000
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_ENV_SIZE=0x80000