net: phy: fixed_phy: constify status argument where possible

Constify the passed struct fixed_phy_status *status where possible.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://patch.msgid.link/d1764b62-8538-408b-a4e3-b63715481a38@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>