Correct SPL uses of SAVE_PREV_BL_FDT_ADDR

This converts 2 usages of this option to the non-SPL form, since there is
no SPL_SAVE_PREV_BL_FDT_ADDR defined in Kconfig

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/board_r.c b/common/board_r.c
index 90e1219..6026e43 100644
--- a/common/board_r.c
+++ b/common/board_r.c
@@ -453,7 +453,7 @@
 			    (unsigned long)map_to_sysmem(gd->fdt_blob));
 
 	#if (CONFIG_IS_ENABLED(SAVE_PREV_BL_INITRAMFS_START_ADDR) || \
-						CONFIG_IS_ENABLED(SAVE_PREV_BL_FDT_ADDR))
+						IS_ENABLED(CONFIG_SAVE_PREV_BL_FDT_ADDR))
 		save_prev_bl_data();
 	#endif