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/board/google/chromebox_panther/Kconfig b/board/google/chromebox_panther/Kconfig
index 875df9d..423a9a2 100644
--- a/board/google/chromebox_panther/Kconfig
+++ b/board/google/chromebox_panther/Kconfig
@@ -12,7 +12,7 @@
 config SYS_CONFIG_NAME
 	default "chromebox_panther"
 
-config SYS_TEXT_BASE
+config TEXT_BASE
 	default 0xfff00000
 
 # Panther actually uses haswell, not ivybridge, so this is just a placeholder