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/ti/ks2_evm/board.c b/board/ti/ks2_evm/board.c
index 5ba3aa3..51e8de4 100644
--- a/board/ti/ks2_evm/board.c
+++ b/board/ti/ks2_evm/board.c
@@ -66,7 +66,7 @@
 
 struct legacy_img_hdr *spl_get_load_buffer(ssize_t offset, size_t size)
 {
-	return (struct legacy_img_hdr *)(CONFIG_SYS_TEXT_BASE);
+	return (struct legacy_img_hdr *)(CONFIG_TEXT_BASE);
 }
 
 int board_init(void)