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/P1020RDB-PD_NAND_defconfig b/configs/P1020RDB-PD_NAND_defconfig
index eb921d9..a4086a3 100644
--- a/configs/P1020RDB-PD_NAND_defconfig
+++ b/configs/P1020RDB-PD_NAND_defconfig
@@ -1,5 +1,5 @@
 CONFIG_PPC=y
-CONFIG_SYS_TEXT_BASE=0x11000000
+CONFIG_TEXT_BASE=0x11000000
 CONFIG_SYS_MALLOC_LEN=0x100000
 CONFIG_ENV_SIZE=0x20000
 CONFIG_ENV_OFFSET=0x100000