net: mdio_bus: Use devm for getting reset GPIO

Commit bafbdd52 ("phylib: Add device reset GPIO support") removed
devm_gpiod_get_optional() in favor of the non-devres managed
fwnode_get_named_gpiod(). When it was kind-of reverted by commit
40ba6a12 ("net: mdio: switch to using gpiod_get_optional()"), the devm
functionality was not reinstated. Nor was the GPIO unclaimed on device
remove. This leads to the GPIO being claimed indefinitely, even when the
device and/or the driver gets removed.

Fixes: bafbdd52 ("phylib: Add device reset GPIO support")
Fixes: 40ba6a12 ("net: mdio: switch to using gpiod_get_optional()")
Cc: Csaba Buday <buday.csaba@prolan.hu>
Signed-off-by: Bence Csókás <csokas.bence@prolan.hu>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20250728153455.47190-2-csokas.bence@prolan.hu


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