ethtool: time to blink provided in seconds not jiffies

When blinking for a duration set by the user, the value specified is in
seconds but it is used as the number of jiffies in the timeout after which
the Physical ID indicator is deactivated.  Fix by converting the timeout
to seconds.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Acked-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>