board_f: Use IS_ENABLED instead of #ifdef in initf_bootstage()

The current implementation makes it look like the 'if (from_spl)' part is
dead code because these features are not enabled for sandbox. We could
enable it for sandbox_spl, but this is not done yet (it requires sharing
memory between SPL and U-Boot proper which is in fact supported).

It is probably nicer to avoid #ifdef anyway. Change it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Coverity (CID: 163244)
Fixes: 824bb1b (bootstage: Support SPL)

common/board_f.c

@@ -706,11 +706,8 @@ static int jump_to_copy(void)
 /* Record the board_init_f() bootstage (after arch_cpu_init()) */
 static int initf_bootstage(void)
 {
-#if defined(CONFIG_SPL_BOOTSTAGE) && defined(CONFIG_BOOTSTAGE_STASH)
-	bool from_spl = true;
-#else
-	bool from_spl = false;
-#endif
+	bool from_spl = IS_ENABLED(CONFIG_SPL_BOOTSTAGE) &&
+			IS_ENABLED(CONFIG_BOOTSTAGE_STASH);
 	int ret;
 
 	ret = bootstage_init(!from_spl);