net: mdio: Remove unnecessary (void*) conversions

No need cast (void*) to (struct xgene_mdio_pdata *).

Signed-off-by: Wu Yunchuan <yunchuan@nfschina.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20230717031212.54991-1-yunchuan@nfschina.com


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