of: fdt: Use IS_ENABLED(CONFIG_BLK_DEV_INITRD) instead of #ifdef

Replace the conditional compilation using "#ifdef CONFIG_BLK_DEV_INITRD"
by a check for "IS_ENABLED(CONFIG_BLK_DEV_INITRD)", to increase compile
coverage and to simplify the code.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/604c13747f09d800da6a7c12f661e1ec146f1dfd.1628670468.git.geert+renesas@glider.be

drivers/of/fdt.c

@@ -896,7 +896,6 @@ const void * __init of_flat_dt_match_machine(const void *default_match,
 	return best_data;
 }
 
-#ifdef CONFIG_BLK_DEV_INITRD
 static void __early_init_dt_declare_initrd(unsigned long start,
 					   unsigned long end)
 {
@@ -922,6 +921,9 @@ static void __init early_init_dt_check_for_initrd(unsigned long node)
 	int len;
 	const __be32 *prop;
 
+	if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))
+		return;
+
 	pr_debug("Looking for initrd properties... ");
 
 	prop = of_get_flat_dt_prop(node, "linux,initrd-start", &len);
@@ -940,11 +942,6 @@ static void __init early_init_dt_check_for_initrd(unsigned long node)
 
 	pr_debug("initrd_start=0x%llx  initrd_end=0x%llx\n", start, end);
 }
-#else
-static inline void early_init_dt_check_for_initrd(unsigned long node)
-{
-}
-#endif /* CONFIG_BLK_DEV_INITRD */
 
 /**
  * early_init_dt_check_for_elfcorehdr - Decode elfcorehdr location from flat