default.xml: Update meta-seco-imx to dunfell branch

This change enable graphics support for C61

default.xml: Update meta-seco-imx for u-boot

Relate-to: https://booting.oniroproject.org/rzr/meta-oniro-blueprint-flutter/-/issues/1
Relate-to: https://gitlab.eclipse.org/groups/eclipse-wg/oniro-wg/proposal-incubation-stage-oniro/-/wikis/UI
Forwarded: eclipse/oniro-core/oniro!78


Signed-off-by: Philippe Coval <philippe.coval.ext@huawei.com>