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/rock2_defconfig b/configs/rock2_defconfig
index 3f06446..1570a71 100644
--- a/configs/rock2_defconfig
+++ b/configs/rock2_defconfig
@@ -2,7 +2,7 @@
 CONFIG_SPL_SKIP_LOWLEVEL_INIT_ONLY=y
 CONFIG_SYS_ARCH_TIMER=y
 CONFIG_ARCH_ROCKCHIP=y
-CONFIG_SYS_TEXT_BASE=0x00000000
+CONFIG_TEXT_BASE=0x00000000
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_ENV_OFFSET=0x3F8000
 CONFIG_DEFAULT_DEVICE_TREE="rk3288-rock2-square"