ice: Don't clear auto_fec bit in ice_cfg_phy_fec()

The driver should never clear the auto_fec_enable bit.

Signed-off-by: Chinh T Cao <chinh.t.cao@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>