Do not try to probe PHY devices if they are masked in phy_mask. This
way we won't try adding devices that are unlikely to be proper PHYs by
default. With this change it still remains possible to add such a
device explicitly either using "miitool" or calling
phy_device_create() explicilty.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>