net: phy: harmonize phy_id{,_mask} data type

Previously phy_id was u32 and phy_id_mask was unsigned int. As the
phy_id_mask defines the important bits of the phy_id (and is therefore
the same size) these two variables should be the same data type.

Signed-off-by: Richard Leitner <richard.leitner@skidata.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>