net: mvpp2: mark phy as invalid in case of missing appropriate driver

net: mvpp2: mark phy as invalid in case of missing appropriate driver

If the phy doesn't match with any existing u-boot drivers, the phy
framework will connect it to the generic one which uid ==
0xffffffff. In this case, act as if the phy wouldn't be declared in
dts. Otherwise, in case of 3310 (for which the driver doesn't exist)
the link is marked as always down. Removing phy entry from dts in case
of 3310 is not a good option because it is required for the
phy_fw_down procedure.

This patch fixes the issue with the link always down on MCBIN board.

nhed: added NULL deref test.

Signed-off-by: Grzegorz Jaszczyk <jaz@semihalf.com>
Reviewed-by: Igal Liberman <igall@marvell.com>
Tested-by: Igal Liberman <igall@marvell.com>
Signed-off-by: Nevo Hed <nhed+github@starry.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>