[prim_sync_reqack_data] Fix SVA checking DST-to-SRC data stability
[prim_sync_reqack_data] Fix SVA checking DST-to-SRC data stability

This commit reduces the window during which data must be stable. Since the
next REQ only takes 1 SRC clock cycle (and 2 DST clock cycles) to cross
over from SRC to DST, it doesn't make sense to check that the data remains
stable for 2 SRC clock cycles after the SRC handshake.

This resolves lowRISC/OpenTitan#4797.

Signed-off-by: Pirmin Vogel <386a7fc8e7338ed7899b4d9883c0ebec5de81366@lowrisc.org>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan