rng: Introduce SPL_DM_RNG

Add SPL variant of DM_RNG so that the DM_RNG can be disabled in SPL
if necessary. This may be necessary due to e.g. size constraints of
the SPL.

Signed-off-by: Marek Vasut <marex@denx.de>

boot/pxe_utils.c

@@ -21,9 +21,7 @@
 #include <errno.h>
 #include <linux/list.h>
 
-#ifdef CONFIG_DM_RNG
 #include <rng.h>
-#endif
 
 #include <splash.h>
 #include <asm/io.h>
@@ -323,7 +321,7 @@ static int label_localboot(struct pxe_label *label)
 
 static void label_boot_kaslrseed(void)
 {
-#ifdef CONFIG_DM_RNG
+#if CONFIG_IS_ENABLED(DM_RNG)
 	ulong fdt_addr;
 	struct fdt_header *working_fdt;
 	size_t n = 0x8;