e1000e: add check on e1e_wphy() return value

Check return value from call to e1e_wphy(). This value is being
checked during previous calls to function e1e_wphy() and it seems
a check was missing here.

Addresses-Coverity-ID: 1226905
Signed-off-by: Gustavo A R Silva <garsilva@embeddedor.com>
Reviewed-by: Ethan Zhao <ethan.zhao@oracle.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>