compatibility_matrix: specify @1.2::ISap directly

@1.4::ISap and @1.3::ISap don't exist, so we can't declare a requirement
for them.

Bug: 135627722
Test: reproduce error with vts_treble_vintf_test and then test to see
    this change fixes it.
Change-Id: I8e48fcaf56701087d5720d5133ffa9b23a4ea31e