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/silinux_ek874_defconfig b/configs/silinux_ek874_defconfig
index b29540a..2ef2f7c 100644
--- a/configs/silinux_ek874_defconfig
+++ b/configs/silinux_ek874_defconfig
@@ -2,7 +2,7 @@
 CONFIG_COUNTER_FREQUENCY=16666666
 CONFIG_ARCH_CPU_INIT=y
 CONFIG_ARCH_RMOBILE=y
-CONFIG_SYS_TEXT_BASE=0x50000000
+CONFIG_TEXT_BASE=0x50000000
 CONFIG_SYS_MALLOC_LEN=0x4000000
 CONFIG_SYS_MALLOC_F_LEN=0x2000
 CONFIG_ENV_SIZE=0x10000