ixgbe: Cleanup unneeded delay in ethtool test

There is a 4 seconds delay in ixgbe_diag_test() that is holding up other
ioctls such as SIOCGIFCONF that Oracle database applications use.
One of Oracle's product runs "ethtool -t ethX online" periodically for
system monitoring and that is impacting database applications that use
SIOCGIFCONF at that same time.

This 4 second delay was needed in out early 1GbE parts to give the PHY
time to recover from a reset.  This code was carried forward to the 10 GbE
driver even it was not needed for the supported PHYs in the ixgbe driver.

CC: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
CC: Jack Vogel <jack.vogel@oracle.com>
Reported-by: Venkat Venkatsubra <venkat.x.venkatsubra@oracle.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>