e1000e: Fix e1000_check_for_copper_link_ich8lan return value.

e1000e_check_for_copper_link() and e1000_check_for_copper_link_ich8lan()
are the two functions that may be assigned to mac.ops.check_for_link when
phy.media_type == e1000_media_type_copper. Commit 19110cfb

 ("e1000e:
Separate signaling for link check/link up") changed the meaning of the
return value of check_for_link for copper media but only adjusted the first
function. This patch adjusts the second function likewise.

Reported-by: Christian Hesse <list@eworm.de>
Reported-by: Gabriel C <nix.or.die@gmail.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=198047
Fixes: 19110cfb

 ("e1000e: Separate signaling for link check/link up")
Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Tested-by: Christian Hesse <list@eworm.de>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>