[IPSCCP] Add missing `AssumptionCacheTracker` dependency

[IPSCCP] Add missing `AssumptionCacheTracker` dependency

Back in August, r340525 introduced a dependency on the assumption
cache tracker in the ipsccp pass, but that commit missed a call to
INITIALIZE_PASS_DEPENDENCY, which leaves the assumption cache
improperly registered if SCCP is the only thing that pulls it in.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358903 91177308-0d34-0410-b5e6-96231b3b80d8