Xilinx changed the way [all_registers -edge_triggered] is treated such
that set_max_delay constraints that use it can cause segmentation and
cause clocks to not be propagated to all endpoints. Changing to
[all_ffs] avoids this potential issue.
Original-commit: 55e422535292c29de00b80f15b0a49ca3fb94f26
Wade Fife
2487e7bdf8