net: phy: broadcom: Correct BCM5221 PHY model detection

Correct detect condition is applied to the entire 5221 family of PHYs.

Fixes: 3abbd069 ("net: phy: broadcom: add support for BCM5221 phy")
Signed-off-by: Jim Liu <jim.t90615@gmail.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>