uboot-imx

fix: missing autoconfig.mk from general Makefile

At the first run of make we generate the autoconf.mk and
autoconf.mk.dep if not already the case and we currently include only
to .dep

In order to use these autogenerated values we need to include it also
even if it's included in config.mk but it's done before their
generation

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>