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/rpi_defconfig b/configs/rpi_defconfig
index 1e11f37..1d356b4 100644
--- a/configs/rpi_defconfig
+++ b/configs/rpi_defconfig
@@ -1,7 +1,7 @@
 CONFIG_ARM=y
 CONFIG_ARCH_CPU_INIT=y
 CONFIG_ARCH_BCM283X=y
-CONFIG_SYS_TEXT_BASE=0x00008000
+CONFIG_TEXT_BASE=0x00008000
 CONFIG_SYS_MALLOC_F_LEN=0x400
 CONFIG_TARGET_RPI=y
 CONFIG_NR_DRAM_BANKS=1