fdt relocate: have more attention to use a bootmap or not

Platforms with flat device tree support can use a bootmap to relocate
the fdt_blob. This is not a must. That's why the relocation function
boot_relocate_fdt() should be use only if CONFIG_OF_LIBFDT was defined
together with CONFIG_SYS_BOOTMAPSZ (see common/cmd_bootm.c).

On MicroBlaze platforms there is no need to use a bootmap to relocate
a fdt blob. So we need a more precise focus on the compilation and usage
of boot_relocate_fdt().

In general it is valid to exclude the function boot_relocate_fdt() if
the bootmap size CONFIG_SYS_BOOTMAPSZ is not defined.

Signed-off-by: Stephan Linz <linz@li-pro.net>
diff --git a/common/image.c b/common/image.c
index ea59730..fcb938b 100644
--- a/common/image.c
+++ b/common/image.c
@@ -1184,6 +1184,7 @@
  *      0 - success
  *      1 - failure
  */
+#if defined(CONFIG_SYS_BOOTMAPSZ)
 int boot_relocate_fdt (struct lmb *lmb, ulong bootmap_base,
 		char **of_flat_tree, ulong *of_size)
 {
@@ -1263,6 +1264,7 @@
 error:
 	return 1;
 }
+#endif /* CONFIG_SYS_BOOTMAPSZ */
 
 /**
  * boot_get_fdt - main fdt handling routine