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/common/board_r.c b/common/board_r.c
index 92ca206..98653de 100644
--- a/common/board_r.c
+++ b/common/board_r.c
@@ -369,7 +369,7 @@
 
 #if defined(CONFIG_OXC) || defined(CONFIG_RMU)
 	/* flash mapped at end of memory map */
-	bd->bi_flashoffset = CONFIG_SYS_TEXT_BASE + flash_size;
+	bd->bi_flashoffset = CONFIG_TEXT_BASE + flash_size;
 #elif CONFIG_SYS_MONITOR_BASE == CONFIG_SYS_FLASH_BASE
 	bd->bi_flashoffset = monitor_flash_len;	/* reserved area for monitor */
 #endif