net: phy: at803x: remove extra space after cast

Remove extra space after cast as reported by checkpatch to keep code
clean.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20231217232739.27065-1-ansuelsmth@gmail.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>