ethtool: make validate_speed accept all speeds between 0 and INT_MAX

BugLink: http://bugs.launchpad.net/bugs/1581132



Devices these days can have any speed and as was recently pointed out
any speed from 0 to INT_MAX is valid so adjust speed validation to
accept such values.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit e02564ee)
Signed-off-by: Andy Gospodarek <gospo@cumulusnetworks.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>