[CSSPGO][llvm-profgen] Fix getCanonicalFnName usage in llvm-profgen

Previously we didn't support to keep the unique linkage name(-funique-internal-linkage-name) in llvm-profgen. As discussed in https://reviews.llvm.org/D96932, we choose to do canonicalization for it.

Now since "selected" is set as the default parameter of getCanonicalFnName in `D96932`, we don't need to add any attribute here for the previous usage and only fix the missing usage in the pseudo probe decoding.

Differential Revision: https://reviews.llvm.org/D98226