MAINTAINERS: Add an entry for the Bananapi machine

MAINTAINERS: Add an entry for the Bananapi machine

This machine was still missing from the MAINTAINERS file. Since there
is likely no active maintainer around for this machine (I didn't spot
any contributions from Qianfan Zhao in the git log after 2023), I'm
suggesting Peter as maintainer with status set to "Odd fixes".

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-id: 20250508072706.114278-1-thuth@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>