[CGP] Fix the crash for combining address mode when having cyclic dependency

In the combination of addressing modes, when replacing the matched phi nodes,
sometimes the phi node to be replaced has been modified. For example,
there’s matcher set [A, B] and [C, A], which will have cyclic dependency:
A is replaced by B and C will be replaced by A. Because we tried to match new phi node
to another new phi node, we should ignore new phi nodes when mapping new phi node to old one.

Reviewed By: skatkov

Differential Revision: https://reviews.llvm.org/D108635