Merge branch 'net-phy-adin1100-fix-powerdown-mode-setting'

Alexander Dahl says:

====================
net: phy: adin1100: Fix powerdown mode setting

while building a new device around the ADIN1100 I noticed some errors in
kernel log when calling `ifdown` on the ethernet device.  Series has a
straight forward fix and an obvious follow-up code simplification.
====================

Link: https://patch.msgid.link/20251119124737.280939-1-ada@thorsis.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>