[Hexagon] Remove -opaque-pointers=0 from tests

Two tests still had opaque-pointers=0:
(1) llvm/test/CodeGen/Hexagon/addrmode.ll
(2) llvm/test/CodeGen/Hexagon/swp-epilog-phi7.ll

Deleted (1) since it no longer exercised the original scenario, modified
(2) to reflect codegen changes.

This fixes https://github.com/llvm/llvm-project/issues/61928