fence_ipmilan: Correct return code for diag operation
Return code for diag operation should be 0.
Replaces commit 8a97abd04b8492310c1095413c5cf26bbf98e395
"diaf" != "diag"
Resolves: rhbz#655764
Signed-off-by: Lon Hohberger <lhh@redhat.com>
Tested-by: Lon Hohberger <lhh@redhat.com>