[X86] Add ISD::FREEZE and ISD::AssertAlign to the list of opcodes that don't...

[X86] Add ISD::FREEZE and ISD::AssertAlign to the list of opcodes that don't guarantee upper 32 bits are zero.

The freeze issue was reported here
https://llvm.discourse.group/t/bug-or-feature-freeze-instruction/3639

I don't have a test for AssertAlign. I just noticed it was missing
and assume it should be similar to the other two Asserts.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D104178