net: phy: fix issue with loading PHY driver w/o initramfs

It was reported that on a system with nfsboot and w/o initramfs network
fails because trying to load the PHY driver returns -ENOENT. Reason was
that due to missing initramfs the modprobe binary isn't available.
So we have to ignore error code -ENOENT.

Fixes: 13d0ab67

 ("net: phy: check return code when requesting PHY driver module")
Reported-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Tested-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>