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/guruplug_defconfig b/configs/guruplug_defconfig
index 5f3424e..794cf4b 100644
--- a/configs/guruplug_defconfig
+++ b/configs/guruplug_defconfig
@@ -4,7 +4,7 @@
 CONFIG_ARCH_CPU_INIT=y
 CONFIG_ARCH_KIRKWOOD=y
 CONFIG_SYS_KWD_CONFIG="board/Marvell/guruplug/kwbimage.cfg"
-CONFIG_SYS_TEXT_BASE=0x600000
+CONFIG_TEXT_BASE=0x600000
 CONFIG_NR_DRAM_BANKS=2
 CONFIG_TARGET_GURUPLUG=y
 CONFIG_ENV_SIZE=0x20000