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/nyan-big_defconfig b/configs/nyan-big_defconfig
index e55da6e..e2e8beb 100644
--- a/configs/nyan-big_defconfig
+++ b/configs/nyan-big_defconfig
@@ -1,7 +1,7 @@
 CONFIG_ARM=y
 CONFIG_SYS_L2CACHE_OFF=y
 CONFIG_ARCH_TEGRA=y
-CONFIG_SYS_TEXT_BASE=0x81000100
+CONFIG_TEXT_BASE=0x81000100
 CONFIG_SYS_MALLOC_LEN=0x2500000
 CONFIG_NR_DRAM_BANKS=2
 CONFIG_ENV_SIZE=0x2000