x86: Don't generate a bootstage report in SPL

This report is normally generated by U-Boot proper. Correct the condition
here so that it respects the Kconfig options for bootstage.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/lib/bootm.c

@@ -35,7 +35,7 @@ void bootm_announce_and_cleanup(void)
 	timestamp_add_now(TS_U_BOOT_START_KERNEL);
 #endif
 	bootstage_mark_name(BOOTSTAGE_ID_BOOTM_HANDOFF, "start_kernel");
-#ifdef CONFIG_BOOTSTAGE_REPORT
+#if CONFIG_IS_ENABLED(BOOTSTAGE_REPORT)
 	bootstage_report();
 #endif