SF: Fix two queries for the past VSYNC's fence

...which did not consider the case of targeting two VSYNCs ahead.

Bug: 241285475
Test: libscheduler_test after Idf9f43b37f3479c94a478d154eaa46f43e0c6c9d
Change-Id: Ib114ffc1866aa32e6d493e06dcf5a27652d19a39
1 file changed