net: phy: mdio-bcm-unimac: remove redundant !timeout check

The check for zero timeout is always true at the end of the proceeding
while loop; the only other exit path in the loop is if the unimac MDIO
is not busy.  Remove the redundant zero timeout check and always
return -ETIMEDOUT on this timeout return path.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>