image: check "bootm_low" and "bootm_size" if "initrd_high" is missing

To boot Linux, we should prevent Initramdisk and FDT from going too
high.

Currently, boot_relocate_fdt() checks "fdt_high" environment first,
and then falls back to getenv_bootm_mapsize() + getenv_bootm_low()
if "fdt_high" is missing.

On the other hand, boot_ramdisk_high() only checks "initrd_high" to
get the address limit for the Initramdisk.  We also want to let this
case fall back to getenv_bootm_mapsize() + getenv_bootm_low().
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

common/image.c

@@ -1113,8 +1113,7 @@ int boot_ramdisk_high(struct lmb *lmb, ulong rd_data, ulong rd_len,
 		if (initrd_high == ~0)
 			initrd_copy_to_ram = 0;
 	} else {
-		/* not set, no restrictions to load high */
-		initrd_high = ~0;
+		initrd_high = getenv_bootm_mapsize() + getenv_bootm_low();
 	}