ipq40xx: fritzrepeater-1200: fix MDIO and PHY probing

ipq40xx: fritzrepeater-1200: fix MDIO and PHY probing

AVM FRITZ!Repeater 1200 does not use QCA807x PHY at all and thus it
disables all of the individual PHY nodes, however this is not enough
anymore since the conversion to PHY package.

Now its now enough to disable the PHY-s in the package alone, but the PHY
package node itself must also be disabled.

Fixes: 1b931c33a28e ("ipq40xx: adapt to new Upstream QCA807x PHY driver")
Fixes: #15355
Link: https://github.com/openwrt/openwrt/pull/15365
Signed-off-by: Robert Marko <robimarko@gmail.com>