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/brppt2_defconfig b/configs/brppt2_defconfig
index e2c36e1..00ef3d9 100644
--- a/configs/brppt2_defconfig
+++ b/configs/brppt2_defconfig
@@ -2,7 +2,7 @@
 # CONFIG_SPL_SYS_THUMB_BUILD is not set
 CONFIG_SYS_L2CACHE_OFF=y
 CONFIG_ARCH_MX6=y
-CONFIG_SYS_TEXT_BASE=0x17800000
+CONFIG_TEXT_BASE=0x17800000
 CONFIG_SYS_MALLOC_LEN=0xa00000
 CONFIG_SYS_MALLOC_F_LEN=0x1000
 CONFIG_SPL_GPIO=y