net: phy: make addr type u8 in phy_package_shared struct

Switch addr type in phy_package_shared struct to u8.

The value is already checked to be non negative and to be less than
PHY_MAX_ADDR, hence u8 is better suited than using int.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>