[mlir] Fix LLVM intrinsic convesion generator for overloadable types.
If an intrinsic has overloadable types like llvm_anyint_ty or
llvm_anyfloat_ty then to getDeclaration() we need to pass a list
of the types that are "undefined" essentially concretizing them.
This patch add support for deriving such types from the MLIR op
that has been matched.
Reviewers: andydavis1, ftynse, nicolasvasilache, antiagainst
Subscribers: mehdi_amini, rriddle, jpienaar, burmako, shauheen, arpith-jacob, mgester, lucyrfox, liufengdb, llvm-commits
Differential Revision: https://reviews.llvm.org/D72974