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/sheevaplug_defconfig b/configs/sheevaplug_defconfig
index 1407034..52f5aba 100644
--- a/configs/sheevaplug_defconfig
+++ b/configs/sheevaplug_defconfig
@@ -8,7 +8,7 @@
 CONFIG_CMDLINE_TAG=y
 CONFIG_INITRD_TAG=y
 CONFIG_SYS_KWD_CONFIG="board/Marvell/sheevaplug/kwbimage.cfg"
-CONFIG_SYS_TEXT_BASE=0x600000
+CONFIG_TEXT_BASE=0x600000
 CONFIG_NR_DRAM_BANKS=2
 CONFIG_TARGET_SHEEVAPLUG=y
 CONFIG_ENV_SIZE=0x20000