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/arch/arm/lib/save_prev_bl_data.c b/arch/arm/lib/save_prev_bl_data.c
index f4ee86a..cd943ee 100644
--- a/arch/arm/lib/save_prev_bl_data.c
+++ b/arch/arm/lib/save_prev_bl_data.c
@@ -60,7 +60,7 @@
 		return -ENODATA;
 	}
 
-	if (CONFIG_IS_ENABLED(SAVE_PREV_BL_FDT_ADDR))
+	if (IS_ENABLED(CONFIG_SAVE_PREV_BL_FDT_ADDR))
 		env_set_addr("prevbl_fdt_addr", (void *)reg0);
 	if (!CONFIG_IS_ENABLED(SAVE_PREV_BL_INITRAMFS_START_ADDR))
 		return 0;