Fix a bug because of b3497bad1221704a5dbc5da0b10f42625f1ad2ed. Before the patch, when GenFds fail, the build continue and return success. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Derek Lin <derek.lin2@hpe.com> Reviewed-by: Bob Feng <bob.c.feng@intel.com>