[Assignment Tracking] Remove assertion from DbgAssignIntrinsic::setAddress

Follow up to https://reviews.llvm.org/D146987.

Remove assertion that the Value must be a pointer type. This fires in
real-world examples e.g. by codegenprepare introducing ptrtoint conversions.

The buildbots have not caught up yet but without this change the test
compiler-rt/test/ubsan/TestCases/TypeCheck/vptr.cpp fails with an ICE.