omap-common: Common function to display die id, replacing omap3-specific version

This introduces omap_die_id_display to display the full die id.
There is no need to store it in an environment variable, that no boot script
is using anyway.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Reviewed-by: Tom Rini <trini@konsulko.com>

board/isee/igep00x0/igep00x0.c

@@ -171,7 +171,7 @@ int misc_init_r(void)
 
 	setup_net_chip();
 
-	dieid_num_r();
+	omap_die_id_display();
 
 	set_fdt();