init-ifupdown: set kernel parameters firstly

init-ifupdown: set kernel parameters firstly

When do ipv6 ready test, some DAD (duplicate address detect) tests failed
since it expect IPV6 will be disabled, but not. even accept_dad has been
set to correct value 2. Further investigation shows the root cause is that
setting the kernel parameter happens after the NIC is upped.

Make kernel parameters be configured before the interfaces is upped, and
duplicate setting the kernel parameters does not have negative effect.

(From OE-Core rev: cabe22b9470e870e63b5ef1ec8349c67b0823abf)

Signed-off-by: Roy.Li <rongqing.li@windriver.com>
Signed-off-by: Jackie Huang <jackie.huang@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>