linux-yocto/5.15: Enable MDIO bus config

Integrating the following commit(s) to linux-yocto/.:

    52919926480 bsp/mti-malta32: enable MDIO for mti-malta32
    963ab127810 bsp/qemuarm64: enable MDIO for qemuarm64
    77d5d5e86c0 cfg/net: introduce mdio fragment

Signed-off-by: Potin Lai <potin.lai.pt@gmail.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 16188887)
Signed-off-by: Steve Sakoman <steve@sakoman.com>